diff --git a/packages/docusaurus-plugin-content-docs/src/__tests__/frontMatter.test.ts b/packages/docusaurus-plugin-content-docs/src/__tests__/frontMatter.test.ts
index 2219ad86af..238cd71390 100644
--- a/packages/docusaurus-plugin-content-docs/src/__tests__/frontMatter.test.ts
+++ b/packages/docusaurus-plugin-content-docs/src/__tests__/frontMatter.test.ts
@@ -186,10 +186,24 @@ describe('validateDocFrontMatter slug', () => {
   });
 });
 
+describe('validateDocFrontMatter sidebar_key', () => {
+  testField({
+    prefix: 'sidebar_key',
+    validFrontMatters: [
+      {sidebar_key: undefined},
+      {sidebar_key: 'Awesome docs'},
+    ],
+    invalidFrontMatters: [[{sidebar_key: ''}, 'is not allowed to be empty']],
+  });
+});
+
 describe('validateDocFrontMatter sidebar_label', () => {
   testField({
     prefix: 'sidebar_label',
-    validFrontMatters: [{sidebar_label: 'Awesome docs'}],
+    validFrontMatters: [
+      {sidebar_label: undefined},
+      {sidebar_label: 'Awesome docs'},
+    ],
     invalidFrontMatters: [[{sidebar_label: ''}, 'is not allowed to be empty']],
   });
 });
diff --git a/packages/docusaurus-plugin-content-docs/src/frontMatter.ts b/packages/docusaurus-plugin-content-docs/src/frontMatter.ts
index de315cddab..0526a5f6b5 100644
--- a/packages/docusaurus-plugin-content-docs/src/frontMatter.ts
+++ b/packages/docusaurus-plugin-content-docs/src/frontMatter.ts
@@ -30,6 +30,7 @@ export const DocFrontMatterSchema = Joi.object<DocFrontMatter>({
   // See https://github.com/facebook/docusaurus/issues/4591#issuecomment-822372398
   description: Joi.string().allow(''),
   slug: Joi.string(),
+  sidebar_key: Joi.string(),
   sidebar_label: Joi.string(),
   sidebar_position: Joi.number(),
   sidebar_class_name: Joi.string(),
diff --git a/packages/docusaurus-plugin-content-docs/src/plugin-content-docs.d.ts b/packages/docusaurus-plugin-content-docs/src/plugin-content-docs.d.ts
index 10f4a84a3b..f89b3f6316 100644
--- a/packages/docusaurus-plugin-content-docs/src/plugin-content-docs.d.ts
+++ b/packages/docusaurus-plugin-content-docs/src/plugin-content-docs.d.ts
@@ -339,7 +339,15 @@ declare module '@docusaurus/plugin-content-docs' {
      * @see {@link DocMetadata.slug}
      */
     slug?: string;
-    /** Customizes the sidebar label for this doc. Will default to its title. */
+    /**
+     * Customizes the sidebar key for this doc,
+     * to uniquely identify it in translations.
+     */
+    sidebar_key?: string;
+    /**
+     * Customizes the sidebar label for this doc.
+     * Will default to its title.
+     */
     sidebar_label?: string;
     /**
      * Controls the position of a doc inside the generated sidebar slice when