diff --git a/docs-yml.schema.json b/docs-yml.schema.json
index 541bb9df61f9..e28ec64145be 100644
--- a/docs-yml.schema.json
+++ b/docs-yml.schema.json
@@ -6053,7 +6053,7 @@
               "type": "null"
             }
           ],
-          "description": "If `mobile-toc` is set to true, a sticky collapsible table of contents bar will be shown on mobile viewports for guide and overview layout pages."
+          "description": "A sticky collapsible table of contents bar is shown on mobile viewports for guide and overview layout pages by default. Set `mobile-toc` to false to disable it."
         }
       },
       "additionalProperties": false
diff --git a/fern/apis/docs-yml/definition/docs.yml b/fern/apis/docs-yml/definition/docs.yml
index d53750d868b1..79179270d847 100644
--- a/fern/apis/docs-yml/definition/docs.yml
+++ b/fern/apis/docs-yml/definition/docs.yml
@@ -969,7 +969,7 @@ types:
         type: optional<boolean>
         availability: in-development
         docs: |
-          If `mobile-toc` is set to true, a sticky collapsible table of contents bar will be shown on mobile viewports for guide and overview layout pages.
+          A sticky collapsible table of contents bar is shown on mobile viewports for guide and overview layout pages by default. Set `mobile-toc` to false to disable it.
 
   DocsSettingsConfig:
     properties:
diff --git a/packages/cli/cli/changes/unreleased/mobile-toc-default-true.yml b/packages/cli/cli/changes/unreleased/mobile-toc-default-true.yml
new file mode 100644
index 000000000000..d36747a7d727
--- /dev/null
+++ b/packages/cli/cli/changes/unreleased/mobile-toc-default-true.yml
@@ -0,0 +1,4 @@
+- summary: |
+    Switch mobile-toc default from opt-in (false) to opt-out (true) so the
+    mobile table of contents is enabled for all documentation sites by default.
+  type: feat
diff --git a/packages/cli/configuration-loader/src/docs-yml/parseDocsConfiguration.ts b/packages/cli/configuration-loader/src/docs-yml/parseDocsConfiguration.ts
index a5312aff4124..94f11c866c33 100644
--- a/packages/cli/configuration-loader/src/docs-yml/parseDocsConfiguration.ts
+++ b/packages/cli/configuration-loader/src/docs-yml/parseDocsConfiguration.ts
@@ -657,7 +657,7 @@ function convertLayoutConfig(
         disableHeader: layout.disableHeader ?? false,
         hideNavLinks: layout.hideNavLinks ?? false,
         hideFeedback: layout.hideFeedback ?? false,
-        mobileToc: layout.mobileToc ?? false,
+        mobileToc: layout.mobileToc ?? true,
         tabsAlignment: resolvedTabsAlignment
     } as unknown as docsYml.ParsedDocsConfiguration["layout"];
 }
diff --git a/packages/cli/configuration/src/docs-yml/schemas/sdk/api/resources/docs/types/LayoutConfig.ts b/packages/cli/configuration/src/docs-yml/schemas/sdk/api/resources/docs/types/LayoutConfig.ts
index 704fc6c69881..0aa1b9a92aeb 100644
--- a/packages/cli/configuration/src/docs-yml/schemas/sdk/api/resources/docs/types/LayoutConfig.ts
+++ b/packages/cli/configuration/src/docs-yml/schemas/sdk/api/resources/docs/types/LayoutConfig.ts
@@ -94,6 +94,6 @@ export interface LayoutConfig {
     hideNavLinks?: boolean;
     /** If `hide-feedback` is set to true, the feedback button will not be rendered. This can be overridden for a specific page using the frontmatter. */
     hideFeedback?: boolean;
-    /** If `mobile-toc` is set to true, a sticky collapsible table of contents bar will be shown on mobile viewports for guide and overview layout pages. */
+    /** A sticky collapsible table of contents bar is shown on mobile viewports for guide and overview layout pages by default. Set `mobile-toc` to false to disable it. */
     mobileToc?: boolean;
 }
diff --git a/packages/cli/workspace/loader/src/docs-yml.schema.json b/packages/cli/workspace/loader/src/docs-yml.schema.json
index 541bb9df61f9..e28ec64145be 100644
--- a/packages/cli/workspace/loader/src/docs-yml.schema.json
+++ b/packages/cli/workspace/loader/src/docs-yml.schema.json
@@ -6053,7 +6053,7 @@
               "type": "null"
             }
           ],
-          "description": "If `mobile-toc` is set to true, a sticky collapsible table of contents bar will be shown on mobile viewports for guide and overview layout pages."
+          "description": "A sticky collapsible table of contents bar is shown on mobile viewports for guide and overview layout pages by default. Set `mobile-toc` to false to disable it."
         }
       },
       "additionalProperties": false