diff --git a/spark/common/src/main/scala/org/apache/sedona/sql/SedonaSqlExtensions.scala b/spark/common/src/main/scala/org/apache/sedona/sql/SedonaSqlExtensions.scala
index 33182a7f90a..d74e3351309 100644
--- a/spark/common/src/main/scala/org/apache/sedona/sql/SedonaSqlExtensions.scala
+++ b/spark/common/src/main/scala/org/apache/sedona/sql/SedonaSqlExtensions.scala
@@ -22,7 +22,7 @@ import org.apache.sedona.spark.SedonaContext
 import org.apache.spark.SparkContext
 import org.apache.spark.sql.SparkSessionExtensions
 import org.apache.spark.sql.parser.ParserFactory
-import org.apache.spark.sql.sedona_sql.optimization.Box2DCastResolutionRule
+import org.apache.spark.sql.sedona_sql.optimization.{Box2DCastResolutionRule, Box3DCastResolutionRule}
 import org.slf4j.{Logger, LoggerFactory}
 
 class SedonaSqlExtensions extends (SparkSessionExtensions => Unit) {
@@ -42,6 +42,11 @@ class SedonaSqlExtensions extends (SparkSessionExtensions => Unit) {
     // refusing arbitrary UDT-to-UDT casts.
     e.injectResolutionRule(_ => new Box2DCastResolutionRule)
 
+    // Resolve geometry→Box3D casts during analysis. Only the forward direction lands here;
+    // the inverse cast (`CAST(box3d AS geometry)`) is deferred until Box3D has an
+    // `ST_GeomFromBox3D` counterpart driven by a concrete consumer.
+    e.injectResolutionRule(_ => new Box3DCastResolutionRule)
+
     // Inject Sedona SQL parser
     if (enableParser) {
       // Try to inject the Sedona SQL parser but gracefully handle initialization failures.
diff --git a/spark/common/src/main/scala/org/apache/spark/sql/sedona_sql/optimization/Box3DCastResolutionRule.scala b/spark/common/src/main/scala/org/apache/spark/sql/sedona_sql/optimization/Box3DCastResolutionRule.scala
new file mode 100644
index 00000000000..c9bc2560976
--- /dev/null
+++ b/spark/common/src/main/scala/org/apache/spark/sql/sedona_sql/optimization/Box3DCastResolutionRule.scala
@@ -0,0 +1,50 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.spark.sql.sedona_sql.optimization
+
+import org.apache.spark.sql.catalyst.expressions.Cast
+import org.apache.spark.sql.catalyst.plans.logical.LogicalPlan
+import org.apache.spark.sql.catalyst.rules.Rule
+import org.apache.spark.sql.sedona_sql.UDT.{Box3DUDT, GeometryUDT}
+import org.apache.spark.sql.sedona_sql.expressions.ST_Box3D
+
+/**
+ * Analyzer rule that resolves Catalyst casts from Geometry to Box3D. Spark's `Cast.canCast`
+ * returns `false` for arbitrary UDT-to-UDT casts, so without this rule the analyzer would reject
+ * `CAST(geom AS box3d)`. We rewrite during analysis (before `CheckAnalysis`) so the downstream
+ * optimizer and codegen path see the expression tree of an ordinary Sedona expression:
+ *
+ *   - `CAST(geom AS box3d)` → `ST_Box3D(geom)` (planar 3D bounding box of the geometry;
+ *     geometries without a Z dimension fold into `zmin = zmax = 0` per PostGIS)
+ *
+ * The inverse direction (`CAST(box3d AS geometry)`) is intentionally deferred until Box3D has a
+ * `ST_GeomFromBox3D` counterpart and a concrete consumer has driven the choice of output geometry
+ * shape. Implicit type coercion is also out of scope here; it requires hooking into Catalyst's
+ * type coercion rules and is tracked separately.
+ */
+class Box3DCastResolutionRule extends Rule[LogicalPlan] {
+
+  override def apply(plan: LogicalPlan): LogicalPlan = plan.transformAllExpressions {
+    case c: Cast
+        if c.child.resolved
+          && c.child.dataType.isInstanceOf[GeometryUDT]
+          && c.dataType.isInstanceOf[Box3DUDT] =>
+      ST_Box3D(Seq(c.child))
+  }
+}
diff --git a/spark/common/src/test/scala/org/apache/sedona/sql/Box3DCastResolutionRuleSuite.scala b/spark/common/src/test/scala/org/apache/sedona/sql/Box3DCastResolutionRuleSuite.scala
new file mode 100644
index 00000000000..b234d843adf
--- /dev/null
+++ b/spark/common/src/test/scala/org/apache/sedona/sql/Box3DCastResolutionRuleSuite.scala
@@ -0,0 +1,68 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.sedona.sql
+
+import org.apache.spark.sql.catalyst.expressions.{Alias, AttributeReference, Cast, Expression, Literal}
+import org.apache.spark.sql.catalyst.plans.logical.{LocalRelation, LogicalPlan, Project}
+import org.apache.spark.sql.sedona_sql.UDT.{Box3DUDT, GeometryUDT}
+import org.apache.spark.sql.sedona_sql.expressions.ST_Box3D
+import org.apache.spark.sql.sedona_sql.optimization.Box3DCastResolutionRule
+import org.apache.spark.sql.types.LongType
+import org.scalatest.funspec.AnyFunSpec
+
+class Box3DCastResolutionRuleSuite extends AnyFunSpec {
+
+  private val rule = new Box3DCastResolutionRule
+
+  private def projectExprPlan(input: AttributeReference, expr: Expression): LogicalPlan = {
+    val rel = LocalRelation(input)
+    Project(Seq(Alias(expr, "out")()), rel)
+  }
+
+  describe("Box3DCastResolutionRule") {
+    it("rewrites Cast(geometry-typed expression, Box3DUDT) into ST_Box3D") {
+      val geomAttr = AttributeReference("g", GeometryUDT(), nullable = true)()
+      val cast = Cast(geomAttr, Box3DUDT)
+      val rewritten = rule(projectExprPlan(geomAttr, cast))
+      val outExpr =
+        rewritten.asInstanceOf[Project].projectList.head.asInstanceOf[Alias].child
+      assert(outExpr.isInstanceOf[ST_Box3D])
+      assert(outExpr.asInstanceOf[ST_Box3D].inputExpressions == Seq(geomAttr))
+      assert(outExpr.dataType.isInstanceOf[Box3DUDT])
+    }
+
+    it("leaves Cast(Box3D-typed expression, GeometryUDT) untouched (inverse cast not in scope)") {
+      val boxAttr = AttributeReference("b", Box3DUDT, nullable = true)()
+      val cast = Cast(boxAttr, GeometryUDT())
+      val rewritten = rule(projectExprPlan(boxAttr, cast))
+      val outExpr =
+        rewritten.asInstanceOf[Project].projectList.head.asInstanceOf[Alias].child
+      assert(outExpr.isInstanceOf[Cast])
+    }
+
+    it("leaves unrelated casts untouched") {
+      val geomAttr = AttributeReference("g", GeometryUDT(), nullable = true)()
+      val cast = Cast(Literal(1), LongType)
+      val rewritten = rule(projectExprPlan(geomAttr, cast))
+      val outExpr =
+        rewritten.asInstanceOf[Project].projectList.head.asInstanceOf[Alias].child
+      assert(outExpr.isInstanceOf[Cast])
+    }
+  }
+}
diff --git a/spark/spark-3.4/src/main/scala/org/apache/sedona/sql/parser/SedonaSqlAstBuilder.scala b/spark/spark-3.4/src/main/scala/org/apache/sedona/sql/parser/SedonaSqlAstBuilder.scala
index eaabd227713..32e63e4f400 100644
--- a/spark/spark-3.4/src/main/scala/org/apache/sedona/sql/parser/SedonaSqlAstBuilder.scala
+++ b/spark/spark-3.4/src/main/scala/org/apache/sedona/sql/parser/SedonaSqlAstBuilder.scala
@@ -20,19 +20,20 @@ package org.apache.sedona.sql.parser
 
 import org.apache.spark.sql.catalyst.parser.SqlBaseParser._
 import org.apache.spark.sql.execution.SparkSqlAstBuilder
-import org.apache.spark.sql.sedona_sql.UDT.{Box2DUDT, GeometryUDT}
+import org.apache.spark.sql.sedona_sql.UDT.{Box2DUDT, Box3DUDT, GeometryUDT}
 import org.apache.spark.sql.types.DataType
 
 class SedonaSqlAstBuilder extends SparkSqlAstBuilder {
 
   /**
-   * Recognize Sedona UDT names (GEOMETRY, BOX2D) as primitive data types so SQL `CAST(... AS
-   * geometry)` / `CAST(... AS box2d)` parse to the matching UDT.
+   * Recognize Sedona UDT names (GEOMETRY, BOX2D, BOX3D) as primitive data types so SQL `CAST(... AS
+   * geometry)` / `CAST(... AS box2d)` / `CAST(... AS box3d)` parse to the matching UDT.
    */
   override def visitPrimitiveDataType(ctx: PrimitiveDataTypeContext): DataType = {
     ctx.getText.toUpperCase() match {
       case "GEOMETRY" => GeometryUDT()
       case "BOX2D" => Box2DUDT
+      case "BOX3D" => Box3DUDT
       case _ => super.visitPrimitiveDataType(ctx)
     }
   }
diff --git a/spark/spark-3.4/src/test/scala/org/apache/sedona/sql/Box3DCastSuite.scala b/spark/spark-3.4/src/test/scala/org/apache/sedona/sql/Box3DCastSuite.scala
new file mode 100644
index 00000000000..cc6cc598081
--- /dev/null
+++ b/spark/spark-3.4/src/test/scala/org/apache/sedona/sql/Box3DCastSuite.scala
@@ -0,0 +1,118 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.sedona.sql
+
+import org.apache.sedona.common.geometryObjects.Box3D
+import org.apache.spark.sql.functions.{col, expr}
+import org.apache.spark.sql.sedona_sql.UDT.Box3DUDT
+
+class Box3DCastSuite extends TestBaseScala {
+
+  /**
+   * SQL `CAST(... AS box3d)` parsing requires Sedona's `SedonaSqlAstBuilder` to be active. The
+   * test base randomizes `spark.sedona.enableParserExtension` across CI runs, and `SparkContext`
+   * is JVM-singleton so the active value can differ from this suite's session-level config. Probe
+   * directly by parsing a tiny CAST: this matches the behavior the SQL tests actually depend on,
+   * and caches the answer for the rest of the suite. DataFrame `.cast(...)` tests run
+   * unconditionally because the resolution rule is always injected.
+   */
+  private lazy val sqlCastSupported: Boolean = {
+    try {
+      sparkSession
+        .sql("SELECT CAST(ST_GeomFromText('POINT (0 0)') AS box3d) AS b")
+        .collect()
+      true
+    } catch {
+      case _: org.apache.spark.sql.catalyst.parser.ParseException => false
+    }
+  }
+
+  describe("Geometry → Box3D Catalyst cast") {
+
+    it("DataFrame .cast(Box3DUDT) rewrites to ST_Box3D") {
+      import sparkSession.implicits._
+      val df = Seq("LINESTRING Z(0 0 -3, 5 10 7)").toDF("wkt")
+      val box = df
+        .select(expr("ST_GeomFromText(wkt)").alias("g"))
+        .select(col("g").cast(Box3DUDT).alias("b"))
+        .collect()
+        .head
+        .getAs[Box3D]("b")
+      assert(box == new Box3D(0.0, 0.0, -3.0, 5.0, 10.0, 7.0))
+    }
+
+    it("DataFrame .cast(Box3DUDT) on XY geometry folds Z = 0") {
+      import sparkSession.implicits._
+      val df = Seq("LINESTRING (0 0, 5 10)").toDF("wkt")
+      val box = df
+        .select(expr("ST_GeomFromText(wkt)").alias("g"))
+        .select(col("g").cast(Box3DUDT).alias("b"))
+        .collect()
+        .head
+        .getAs[Box3D]("b")
+      assert(box == new Box3D(0.0, 0.0, 0.0, 5.0, 10.0, 0.0))
+    }
+
+    it("DataFrame .cast(Box3DUDT) on NULL geometry returns null") {
+      val box = sparkSession
+        .sql("SELECT ST_GeomFromText(NULL) AS g")
+        .select(col("g").cast(Box3DUDT).alias("b"))
+        .collect()
+        .head
+        .getAs[Box3D]("b")
+      assert(box == null)
+    }
+
+    it("SQL CAST(geom AS box3d) returns the 3D bbox") {
+      assume(
+        sqlCastSupported,
+        "Sedona SQL parser extension is required for `CAST(... AS box3d)` syntax")
+      val box = sparkSession
+        .sql("SELECT CAST(ST_GeomFromText('LINESTRING Z(0 0 -3, 5 10 7)') AS box3d) AS b")
+        .collect()
+        .head
+        .getAs[Box3D]("b")
+      assert(box == new Box3D(0.0, 0.0, -3.0, 5.0, 10.0, 7.0))
+    }
+
+    it("SQL CAST(geom AS box3d) on XY geometry folds Z = 0") {
+      assume(
+        sqlCastSupported,
+        "Sedona SQL parser extension is required for `CAST(... AS box3d)` syntax")
+      val box = sparkSession
+        .sql("SELECT CAST(ST_GeomFromText('LINESTRING (0 0, 5 10)') AS box3d) AS b")
+        .collect()
+        .head
+        .getAs[Box3D]("b")
+      assert(box == new Box3D(0.0, 0.0, 0.0, 5.0, 10.0, 0.0))
+    }
+
+    it("SQL CAST(NULL geometry AS box3d) returns null") {
+      assume(
+        sqlCastSupported,
+        "Sedona SQL parser extension is required for `CAST(... AS box3d)` syntax")
+      val box = sparkSession
+        .sql("SELECT CAST(ST_GeomFromText(NULL) AS box3d) AS b")
+        .collect()
+        .head
+        .getAs[Box3D]("b")
+      assert(box == null)
+    }
+  }
+}
diff --git a/spark/spark-3.5/src/main/scala/org/apache/sedona/sql/parser/SedonaSqlAstBuilder.scala b/spark/spark-3.5/src/main/scala/org/apache/sedona/sql/parser/SedonaSqlAstBuilder.scala
index eaabd227713..b6a87dfa4f7 100644
--- a/spark/spark-3.5/src/main/scala/org/apache/sedona/sql/parser/SedonaSqlAstBuilder.scala
+++ b/spark/spark-3.5/src/main/scala/org/apache/sedona/sql/parser/SedonaSqlAstBuilder.scala
@@ -20,19 +20,20 @@ package org.apache.sedona.sql.parser
 
 import org.apache.spark.sql.catalyst.parser.SqlBaseParser._
 import org.apache.spark.sql.execution.SparkSqlAstBuilder
-import org.apache.spark.sql.sedona_sql.UDT.{Box2DUDT, GeometryUDT}
+import org.apache.spark.sql.sedona_sql.UDT.{Box2DUDT, Box3DUDT, GeometryUDT}
 import org.apache.spark.sql.types.DataType
 
 class SedonaSqlAstBuilder extends SparkSqlAstBuilder {
 
   /**
-   * Recognize Sedona UDT names (GEOMETRY, BOX2D) as primitive data types so SQL `CAST(... AS
-   * geometry)` / `CAST(... AS box2d)` parse to the matching UDT.
+   * Recognize Sedona UDT names (GEOMETRY, BOX2D, BOX3D) as primitive data types so SQL `CAST(...
+   * AS geometry)` / `CAST(... AS box2d)` / `CAST(... AS box3d)` parse to the matching UDT.
    */
   override def visitPrimitiveDataType(ctx: PrimitiveDataTypeContext): DataType = {
     ctx.getText.toUpperCase() match {
       case "GEOMETRY" => GeometryUDT()
       case "BOX2D" => Box2DUDT
+      case "BOX3D" => Box3DUDT
       case _ => super.visitPrimitiveDataType(ctx)
     }
   }
diff --git a/spark/spark-3.5/src/test/scala/org/apache/sedona/sql/Box3DCastSuite.scala b/spark/spark-3.5/src/test/scala/org/apache/sedona/sql/Box3DCastSuite.scala
new file mode 100644
index 00000000000..cc6cc598081
--- /dev/null
+++ b/spark/spark-3.5/src/test/scala/org/apache/sedona/sql/Box3DCastSuite.scala
@@ -0,0 +1,118 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.sedona.sql
+
+import org.apache.sedona.common.geometryObjects.Box3D
+import org.apache.spark.sql.functions.{col, expr}
+import org.apache.spark.sql.sedona_sql.UDT.Box3DUDT
+
+class Box3DCastSuite extends TestBaseScala {
+
+  /**
+   * SQL `CAST(... AS box3d)` parsing requires Sedona's `SedonaSqlAstBuilder` to be active. The
+   * test base randomizes `spark.sedona.enableParserExtension` across CI runs, and `SparkContext`
+   * is JVM-singleton so the active value can differ from this suite's session-level config. Probe
+   * directly by parsing a tiny CAST: this matches the behavior the SQL tests actually depend on,
+   * and caches the answer for the rest of the suite. DataFrame `.cast(...)` tests run
+   * unconditionally because the resolution rule is always injected.
+   */
+  private lazy val sqlCastSupported: Boolean = {
+    try {
+      sparkSession
+        .sql("SELECT CAST(ST_GeomFromText('POINT (0 0)') AS box3d) AS b")
+        .collect()
+      true
+    } catch {
+      case _: org.apache.spark.sql.catalyst.parser.ParseException => false
+    }
+  }
+
+  describe("Geometry → Box3D Catalyst cast") {
+
+    it("DataFrame .cast(Box3DUDT) rewrites to ST_Box3D") {
+      import sparkSession.implicits._
+      val df = Seq("LINESTRING Z(0 0 -3, 5 10 7)").toDF("wkt")
+      val box = df
+        .select(expr("ST_GeomFromText(wkt)").alias("g"))
+        .select(col("g").cast(Box3DUDT).alias("b"))
+        .collect()
+        .head
+        .getAs[Box3D]("b")
+      assert(box == new Box3D(0.0, 0.0, -3.0, 5.0, 10.0, 7.0))
+    }
+
+    it("DataFrame .cast(Box3DUDT) on XY geometry folds Z = 0") {
+      import sparkSession.implicits._
+      val df = Seq("LINESTRING (0 0, 5 10)").toDF("wkt")
+      val box = df
+        .select(expr("ST_GeomFromText(wkt)").alias("g"))
+        .select(col("g").cast(Box3DUDT).alias("b"))
+        .collect()
+        .head
+        .getAs[Box3D]("b")
+      assert(box == new Box3D(0.0, 0.0, 0.0, 5.0, 10.0, 0.0))
+    }
+
+    it("DataFrame .cast(Box3DUDT) on NULL geometry returns null") {
+      val box = sparkSession
+        .sql("SELECT ST_GeomFromText(NULL) AS g")
+        .select(col("g").cast(Box3DUDT).alias("b"))
+        .collect()
+        .head
+        .getAs[Box3D]("b")
+      assert(box == null)
+    }
+
+    it("SQL CAST(geom AS box3d) returns the 3D bbox") {
+      assume(
+        sqlCastSupported,
+        "Sedona SQL parser extension is required for `CAST(... AS box3d)` syntax")
+      val box = sparkSession
+        .sql("SELECT CAST(ST_GeomFromText('LINESTRING Z(0 0 -3, 5 10 7)') AS box3d) AS b")
+        .collect()
+        .head
+        .getAs[Box3D]("b")
+      assert(box == new Box3D(0.0, 0.0, -3.0, 5.0, 10.0, 7.0))
+    }
+
+    it("SQL CAST(geom AS box3d) on XY geometry folds Z = 0") {
+      assume(
+        sqlCastSupported,
+        "Sedona SQL parser extension is required for `CAST(... AS box3d)` syntax")
+      val box = sparkSession
+        .sql("SELECT CAST(ST_GeomFromText('LINESTRING (0 0, 5 10)') AS box3d) AS b")
+        .collect()
+        .head
+        .getAs[Box3D]("b")
+      assert(box == new Box3D(0.0, 0.0, 0.0, 5.0, 10.0, 0.0))
+    }
+
+    it("SQL CAST(NULL geometry AS box3d) returns null") {
+      assume(
+        sqlCastSupported,
+        "Sedona SQL parser extension is required for `CAST(... AS box3d)` syntax")
+      val box = sparkSession
+        .sql("SELECT CAST(ST_GeomFromText(NULL) AS box3d) AS b")
+        .collect()
+        .head
+        .getAs[Box3D]("b")
+      assert(box == null)
+    }
+  }
+}
diff --git a/spark/spark-4.0/src/main/scala/org/apache/sedona/sql/parser/SedonaSqlAstBuilder.scala b/spark/spark-4.0/src/main/scala/org/apache/sedona/sql/parser/SedonaSqlAstBuilder.scala
index eaabd227713..32e63e4f400 100644
--- a/spark/spark-4.0/src/main/scala/org/apache/sedona/sql/parser/SedonaSqlAstBuilder.scala
+++ b/spark/spark-4.0/src/main/scala/org/apache/sedona/sql/parser/SedonaSqlAstBuilder.scala
@@ -20,19 +20,20 @@ package org.apache.sedona.sql.parser
 
 import org.apache.spark.sql.catalyst.parser.SqlBaseParser._
 import org.apache.spark.sql.execution.SparkSqlAstBuilder
-import org.apache.spark.sql.sedona_sql.UDT.{Box2DUDT, GeometryUDT}
+import org.apache.spark.sql.sedona_sql.UDT.{Box2DUDT, Box3DUDT, GeometryUDT}
 import org.apache.spark.sql.types.DataType
 
 class SedonaSqlAstBuilder extends SparkSqlAstBuilder {
 
   /**
-   * Recognize Sedona UDT names (GEOMETRY, BOX2D) as primitive data types so SQL `CAST(... AS
-   * geometry)` / `CAST(... AS box2d)` parse to the matching UDT.
+   * Recognize Sedona UDT names (GEOMETRY, BOX2D, BOX3D) as primitive data types so SQL `CAST(... AS
+   * geometry)` / `CAST(... AS box2d)` / `CAST(... AS box3d)` parse to the matching UDT.
    */
   override def visitPrimitiveDataType(ctx: PrimitiveDataTypeContext): DataType = {
     ctx.getText.toUpperCase() match {
       case "GEOMETRY" => GeometryUDT()
       case "BOX2D" => Box2DUDT
+      case "BOX3D" => Box3DUDT
       case _ => super.visitPrimitiveDataType(ctx)
     }
   }
diff --git a/spark/spark-4.0/src/test/scala/org/apache/sedona/sql/Box3DCastSuite.scala b/spark/spark-4.0/src/test/scala/org/apache/sedona/sql/Box3DCastSuite.scala
new file mode 100644
index 00000000000..cc6cc598081
--- /dev/null
+++ b/spark/spark-4.0/src/test/scala/org/apache/sedona/sql/Box3DCastSuite.scala
@@ -0,0 +1,118 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.sedona.sql
+
+import org.apache.sedona.common.geometryObjects.Box3D
+import org.apache.spark.sql.functions.{col, expr}
+import org.apache.spark.sql.sedona_sql.UDT.Box3DUDT
+
+class Box3DCastSuite extends TestBaseScala {
+
+  /**
+   * SQL `CAST(... AS box3d)` parsing requires Sedona's `SedonaSqlAstBuilder` to be active. The
+   * test base randomizes `spark.sedona.enableParserExtension` across CI runs, and `SparkContext`
+   * is JVM-singleton so the active value can differ from this suite's session-level config. Probe
+   * directly by parsing a tiny CAST: this matches the behavior the SQL tests actually depend on,
+   * and caches the answer for the rest of the suite. DataFrame `.cast(...)` tests run
+   * unconditionally because the resolution rule is always injected.
+   */
+  private lazy val sqlCastSupported: Boolean = {
+    try {
+      sparkSession
+        .sql("SELECT CAST(ST_GeomFromText('POINT (0 0)') AS box3d) AS b")
+        .collect()
+      true
+    } catch {
+      case _: org.apache.spark.sql.catalyst.parser.ParseException => false
+    }
+  }
+
+  describe("Geometry → Box3D Catalyst cast") {
+
+    it("DataFrame .cast(Box3DUDT) rewrites to ST_Box3D") {
+      import sparkSession.implicits._
+      val df = Seq("LINESTRING Z(0 0 -3, 5 10 7)").toDF("wkt")
+      val box = df
+        .select(expr("ST_GeomFromText(wkt)").alias("g"))
+        .select(col("g").cast(Box3DUDT).alias("b"))
+        .collect()
+        .head
+        .getAs[Box3D]("b")
+      assert(box == new Box3D(0.0, 0.0, -3.0, 5.0, 10.0, 7.0))
+    }
+
+    it("DataFrame .cast(Box3DUDT) on XY geometry folds Z = 0") {
+      import sparkSession.implicits._
+      val df = Seq("LINESTRING (0 0, 5 10)").toDF("wkt")
+      val box = df
+        .select(expr("ST_GeomFromText(wkt)").alias("g"))
+        .select(col("g").cast(Box3DUDT).alias("b"))
+        .collect()
+        .head
+        .getAs[Box3D]("b")
+      assert(box == new Box3D(0.0, 0.0, 0.0, 5.0, 10.0, 0.0))
+    }
+
+    it("DataFrame .cast(Box3DUDT) on NULL geometry returns null") {
+      val box = sparkSession
+        .sql("SELECT ST_GeomFromText(NULL) AS g")
+        .select(col("g").cast(Box3DUDT).alias("b"))
+        .collect()
+        .head
+        .getAs[Box3D]("b")
+      assert(box == null)
+    }
+
+    it("SQL CAST(geom AS box3d) returns the 3D bbox") {
+      assume(
+        sqlCastSupported,
+        "Sedona SQL parser extension is required for `CAST(... AS box3d)` syntax")
+      val box = sparkSession
+        .sql("SELECT CAST(ST_GeomFromText('LINESTRING Z(0 0 -3, 5 10 7)') AS box3d) AS b")
+        .collect()
+        .head
+        .getAs[Box3D]("b")
+      assert(box == new Box3D(0.0, 0.0, -3.0, 5.0, 10.0, 7.0))
+    }
+
+    it("SQL CAST(geom AS box3d) on XY geometry folds Z = 0") {
+      assume(
+        sqlCastSupported,
+        "Sedona SQL parser extension is required for `CAST(... AS box3d)` syntax")
+      val box = sparkSession
+        .sql("SELECT CAST(ST_GeomFromText('LINESTRING (0 0, 5 10)') AS box3d) AS b")
+        .collect()
+        .head
+        .getAs[Box3D]("b")
+      assert(box == new Box3D(0.0, 0.0, 0.0, 5.0, 10.0, 0.0))
+    }
+
+    it("SQL CAST(NULL geometry AS box3d) returns null") {
+      assume(
+        sqlCastSupported,
+        "Sedona SQL parser extension is required for `CAST(... AS box3d)` syntax")
+      val box = sparkSession
+        .sql("SELECT CAST(ST_GeomFromText(NULL) AS box3d) AS b")
+        .collect()
+        .head
+        .getAs[Box3D]("b")
+      assert(box == null)
+    }
+  }
+}
diff --git a/spark/spark-4.1/src/main/scala/org/apache/sedona/sql/parser/SedonaSqlAstBuilder.scala b/spark/spark-4.1/src/main/scala/org/apache/sedona/sql/parser/SedonaSqlAstBuilder.scala
index eaabd227713..32e63e4f400 100644
--- a/spark/spark-4.1/src/main/scala/org/apache/sedona/sql/parser/SedonaSqlAstBuilder.scala
+++ b/spark/spark-4.1/src/main/scala/org/apache/sedona/sql/parser/SedonaSqlAstBuilder.scala
@@ -20,19 +20,20 @@ package org.apache.sedona.sql.parser
 
 import org.apache.spark.sql.catalyst.parser.SqlBaseParser._
 import org.apache.spark.sql.execution.SparkSqlAstBuilder
-import org.apache.spark.sql.sedona_sql.UDT.{Box2DUDT, GeometryUDT}
+import org.apache.spark.sql.sedona_sql.UDT.{Box2DUDT, Box3DUDT, GeometryUDT}
 import org.apache.spark.sql.types.DataType
 
 class SedonaSqlAstBuilder extends SparkSqlAstBuilder {
 
   /**
-   * Recognize Sedona UDT names (GEOMETRY, BOX2D) as primitive data types so SQL `CAST(... AS
-   * geometry)` / `CAST(... AS box2d)` parse to the matching UDT.
+   * Recognize Sedona UDT names (GEOMETRY, BOX2D, BOX3D) as primitive data types so SQL `CAST(... AS
+   * geometry)` / `CAST(... AS box2d)` / `CAST(... AS box3d)` parse to the matching UDT.
    */
   override def visitPrimitiveDataType(ctx: PrimitiveDataTypeContext): DataType = {
     ctx.getText.toUpperCase() match {
       case "GEOMETRY" => GeometryUDT()
       case "BOX2D" => Box2DUDT
+      case "BOX3D" => Box3DUDT
       case _ => super.visitPrimitiveDataType(ctx)
     }
   }
diff --git a/spark/spark-4.1/src/test/scala/org/apache/sedona/sql/Box3DCastSuite.scala b/spark/spark-4.1/src/test/scala/org/apache/sedona/sql/Box3DCastSuite.scala
new file mode 100644
index 00000000000..cc6cc598081
--- /dev/null
+++ b/spark/spark-4.1/src/test/scala/org/apache/sedona/sql/Box3DCastSuite.scala
@@ -0,0 +1,118 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.sedona.sql
+
+import org.apache.sedona.common.geometryObjects.Box3D
+import org.apache.spark.sql.functions.{col, expr}
+import org.apache.spark.sql.sedona_sql.UDT.Box3DUDT
+
+class Box3DCastSuite extends TestBaseScala {
+
+  /**
+   * SQL `CAST(... AS box3d)` parsing requires Sedona's `SedonaSqlAstBuilder` to be active. The
+   * test base randomizes `spark.sedona.enableParserExtension` across CI runs, and `SparkContext`
+   * is JVM-singleton so the active value can differ from this suite's session-level config. Probe
+   * directly by parsing a tiny CAST: this matches the behavior the SQL tests actually depend on,
+   * and caches the answer for the rest of the suite. DataFrame `.cast(...)` tests run
+   * unconditionally because the resolution rule is always injected.
+   */
+  private lazy val sqlCastSupported: Boolean = {
+    try {
+      sparkSession
+        .sql("SELECT CAST(ST_GeomFromText('POINT (0 0)') AS box3d) AS b")
+        .collect()
+      true
+    } catch {
+      case _: org.apache.spark.sql.catalyst.parser.ParseException => false
+    }
+  }
+
+  describe("Geometry → Box3D Catalyst cast") {
+
+    it("DataFrame .cast(Box3DUDT) rewrites to ST_Box3D") {
+      import sparkSession.implicits._
+      val df = Seq("LINESTRING Z(0 0 -3, 5 10 7)").toDF("wkt")
+      val box = df
+        .select(expr("ST_GeomFromText(wkt)").alias("g"))
+        .select(col("g").cast(Box3DUDT).alias("b"))
+        .collect()
+        .head
+        .getAs[Box3D]("b")
+      assert(box == new Box3D(0.0, 0.0, -3.0, 5.0, 10.0, 7.0))
+    }
+
+    it("DataFrame .cast(Box3DUDT) on XY geometry folds Z = 0") {
+      import sparkSession.implicits._
+      val df = Seq("LINESTRING (0 0, 5 10)").toDF("wkt")
+      val box = df
+        .select(expr("ST_GeomFromText(wkt)").alias("g"))
+        .select(col("g").cast(Box3DUDT).alias("b"))
+        .collect()
+        .head
+        .getAs[Box3D]("b")
+      assert(box == new Box3D(0.0, 0.0, 0.0, 5.0, 10.0, 0.0))
+    }
+
+    it("DataFrame .cast(Box3DUDT) on NULL geometry returns null") {
+      val box = sparkSession
+        .sql("SELECT ST_GeomFromText(NULL) AS g")
+        .select(col("g").cast(Box3DUDT).alias("b"))
+        .collect()
+        .head
+        .getAs[Box3D]("b")
+      assert(box == null)
+    }
+
+    it("SQL CAST(geom AS box3d) returns the 3D bbox") {
+      assume(
+        sqlCastSupported,
+        "Sedona SQL parser extension is required for `CAST(... AS box3d)` syntax")
+      val box = sparkSession
+        .sql("SELECT CAST(ST_GeomFromText('LINESTRING Z(0 0 -3, 5 10 7)') AS box3d) AS b")
+        .collect()
+        .head
+        .getAs[Box3D]("b")
+      assert(box == new Box3D(0.0, 0.0, -3.0, 5.0, 10.0, 7.0))
+    }
+
+    it("SQL CAST(geom AS box3d) on XY geometry folds Z = 0") {
+      assume(
+        sqlCastSupported,
+        "Sedona SQL parser extension is required for `CAST(... AS box3d)` syntax")
+      val box = sparkSession
+        .sql("SELECT CAST(ST_GeomFromText('LINESTRING (0 0, 5 10)') AS box3d) AS b")
+        .collect()
+        .head
+        .getAs[Box3D]("b")
+      assert(box == new Box3D(0.0, 0.0, 0.0, 5.0, 10.0, 0.0))
+    }
+
+    it("SQL CAST(NULL geometry AS box3d) returns null") {
+      assume(
+        sqlCastSupported,
+        "Sedona SQL parser extension is required for `CAST(... AS box3d)` syntax")
+      val box = sparkSession
+        .sql("SELECT CAST(ST_GeomFromText(NULL) AS box3d) AS b")
+        .collect()
+        .head
+        .getAs[Box3D]("b")
+      assert(box == null)
+    }
+  }
+}