diff --git a/packages/docusaurus-plugin-content-docs/src/__tests__/__fixtures__/sidebars/sidebars-category.js b/packages/docusaurus-plugin-content-docs/src/__tests__/__fixtures__/sidebars/sidebars-category.js
index 975f1203fe..402803c0c4 100644
--- a/packages/docusaurus-plugin-content-docs/src/__tests__/__fixtures__/sidebars/sidebars-category.js
+++ b/packages/docusaurus-plugin-content-docs/src/__tests__/__fixtures__/sidebars/sidebars-category.js
@@ -9,30 +9,25 @@ module.exports = {
   docs: [
     {
       type: 'category',
-      collapsed: true,
       label: 'level 1',
       items: [
         'a',
         {
           type: 'category',
-          collapsed: true,
           label: 'level 2',
           items: [
             {
               type: 'category',
-              collapsed: true,
               label: 'level 3',
               items: [
                 'c',
                 {
                   type: 'category',
-                  collapsed: true,
                   label: 'level 4',
                   items: [
                     'd',
                     {
                       type: 'category',
-                      collapsed: true,
                       label: 'deeper more more',
                       items: ['e'],
                     },
diff --git a/packages/docusaurus-plugin-content-docs/src/__tests__/__fixtures__/sidebars/sidebars-collapsed-first-level.json b/packages/docusaurus-plugin-content-docs/src/__tests__/__fixtures__/sidebars/sidebars-collapsed-first-level.json
deleted file mode 100644
index 1251a7d454..0000000000
--- a/packages/docusaurus-plugin-content-docs/src/__tests__/__fixtures__/sidebars/sidebars-collapsed-first-level.json
+++ /dev/null
@@ -1,20 +0,0 @@
-{
-    "docs": [
-        {
-            "type": "category",
-            "label": "Introduction",
-            "items": [
-                "doc1"
-            ],
-            "collapsed": false
-        },
-        {
-            "type": "category",
-            "label": "Powering MDX",
-            "items": [
-                "doc2"
-            ],
-            "collapsed": false
-        }
-    ]
-}
\ No newline at end of file
diff --git a/packages/docusaurus-plugin-content-docs/src/__tests__/__fixtures__/sidebars/sidebars-collapsed.json b/packages/docusaurus-plugin-content-docs/src/__tests__/__fixtures__/sidebars/sidebars-collapsed.json
deleted file mode 100644
index 2199c5f557..0000000000
--- a/packages/docusaurus-plugin-content-docs/src/__tests__/__fixtures__/sidebars/sidebars-collapsed.json
+++ /dev/null
@@ -1,21 +0,0 @@
-{
-    "docs": {
-      "Test": [
-        {
-          "type": "category",
-          "label": "Introduction",
-          "items": ["doc1"],
-          "collapsed": false
-        }
-      ],
-      "Reference": [
-        {
-          "type": "category",
-          "label": "Powering MDX",
-          "items": ["doc2"],
-          "collapsed": false
-        }
-      ]
-    }
-  }
-  
\ No newline at end of file
diff --git a/packages/docusaurus-plugin-content-docs/src/__tests__/__snapshots__/index.test.ts.snap b/packages/docusaurus-plugin-content-docs/src/__tests__/__snapshots__/index.test.ts.snap
index dd85d4c264..11d22b0c99 100644
--- a/packages/docusaurus-plugin-content-docs/src/__tests__/__snapshots__/index.test.ts.snap
+++ b/packages/docusaurus-plugin-content-docs/src/__tests__/__snapshots__/index.test.ts.snap
@@ -4,7 +4,6 @@ exports[`simple website content 1`] = `
 Object {
   "docs": Array [
     Object {
-      "collapsed": true,
       "items": Array [
         Object {
           "items": Array [
@@ -37,7 +36,6 @@ Object {
       "type": "category",
     },
     Object {
-      "collapsed": true,
       "items": Array [
         Object {
           "href": "/docs/hello",
@@ -202,7 +200,6 @@ exports[`versioned website content: all sidebars 1`] = `
 Object {
   "docs": Array [
     Object {
-      "collapsed": true,
       "items": Array [
         Object {
           "href": "/docs/next/foo/bar",
@@ -214,7 +211,6 @@ Object {
       "type": "category",
     },
     Object {
-      "collapsed": true,
       "items": Array [
         Object {
           "href": "/docs/next/hello",
@@ -228,7 +224,6 @@ Object {
   ],
   "version-1.0.0/docs": Array [
     Object {
-      "collapsed": true,
       "items": Array [
         Object {
           "href": "/docs/1.0.0/foo/bar",
@@ -245,7 +240,6 @@ Object {
       "type": "category",
     },
     Object {
-      "collapsed": true,
       "items": Array [
         Object {
           "href": "/docs/1.0.0/hello",
@@ -259,7 +253,6 @@ Object {
   ],
   "version-1.0.1/docs": Array [
     Object {
-      "collapsed": true,
       "items": Array [
         Object {
           "href": "/docs/foo/bar",
@@ -271,7 +264,6 @@ Object {
       "type": "category",
     },
     Object {
-      "collapsed": true,
       "items": Array [
         Object {
           "href": "/docs/hello",
@@ -291,7 +283,6 @@ Object {
   "docsSidebars": Object {
     "version-1.0.0/docs": Array [
       Object {
-        "collapsed": true,
         "items": Array [
           Object {
             "href": "/docs/1.0.0/foo/bar",
@@ -308,7 +299,6 @@ Object {
         "type": "category",
       },
       Object {
-        "collapsed": true,
         "items": Array [
           Object {
             "href": "/docs/1.0.0/hello",
@@ -335,7 +325,6 @@ Object {
   "docsSidebars": Object {
     "version-1.0.1/docs": Array [
       Object {
-        "collapsed": true,
         "items": Array [
           Object {
             "href": "/docs/foo/bar",
@@ -347,7 +336,6 @@ Object {
         "type": "category",
       },
       Object {
-        "collapsed": true,
         "items": Array [
           Object {
             "href": "/docs/hello",
@@ -373,7 +361,6 @@ Object {
   "docsSidebars": Object {
     "docs": Array [
       Object {
-        "collapsed": true,
         "items": Array [
           Object {
             "href": "/docs/next/foo/bar",
@@ -385,7 +372,6 @@ Object {
         "type": "category",
       },
       Object {
-        "collapsed": true,
         "items": Array [
           Object {
             "href": "/docs/next/hello",
diff --git a/packages/docusaurus-plugin-content-docs/src/__tests__/__snapshots__/sidebars.test.ts.snap b/packages/docusaurus-plugin-content-docs/src/__tests__/__snapshots__/sidebars.test.ts.snap
index 0aa670c44b..e0bc01bdc9 100644
--- a/packages/docusaurus-plugin-content-docs/src/__tests__/__snapshots__/sidebars.test.ts.snap
+++ b/packages/docusaurus-plugin-content-docs/src/__tests__/__snapshots__/sidebars.test.ts.snap
@@ -4,7 +4,6 @@ exports[`loadSidebars sidebars link 1`] = `
 Object {
   "docs": Array [
     Object {
-      "collapsed": true,
       "items": Array [
         Object {
           "href": "https://github.com",
@@ -19,107 +18,30 @@ Object {
 }
 `;
 
-exports[`loadSidebars sidebars with category.collapsed property 1`] = `
-Object {
-  "docs": Array [
-    Object {
-      "collapsed": true,
-      "items": Array [
-        Object {
-          "collapsed": false,
-          "items": Array [
-            Object {
-              "id": "doc1",
-              "type": "doc",
-            },
-          ],
-          "label": "Introduction",
-          "type": "category",
-        },
-      ],
-      "label": "Test",
-      "type": "category",
-    },
-    Object {
-      "collapsed": true,
-      "items": Array [
-        Object {
-          "collapsed": false,
-          "items": Array [
-            Object {
-              "id": "doc2",
-              "type": "doc",
-            },
-          ],
-          "label": "Powering MDX",
-          "type": "category",
-        },
-      ],
-      "label": "Reference",
-      "type": "category",
-    },
-  ],
-}
-`;
-
-exports[`loadSidebars sidebars with category.collapsed property at first level 1`] = `
-Object {
-  "docs": Array [
-    Object {
-      "collapsed": false,
-      "items": Array [
-        Object {
-          "id": "doc1",
-          "type": "doc",
-        },
-      ],
-      "label": "Introduction",
-      "type": "category",
-    },
-    Object {
-      "collapsed": false,
-      "items": Array [
-        Object {
-          "id": "doc2",
-          "type": "doc",
-        },
-      ],
-      "label": "Powering MDX",
-      "type": "category",
-    },
-  ],
-}
-`;
-
 exports[`loadSidebars sidebars with deep level of category 1`] = `
 Object {
   "docs": Array [
     Object {
-      "collapsed": true,
       "items": Array [
         Object {
           "id": "a",
           "type": "doc",
         },
         Object {
-          "collapsed": true,
           "items": Array [
             Object {
-              "collapsed": true,
               "items": Array [
                 Object {
                   "id": "c",
                   "type": "doc",
                 },
                 Object {
-                  "collapsed": true,
                   "items": Array [
                     Object {
                       "id": "d",
                       "type": "doc",
                     },
                     Object {
-                      "collapsed": true,
                       "items": Array [
                         Object {
                           "id": "e",
@@ -178,7 +100,6 @@ exports[`loadSidebars sidebars with known sidebar item type 1`] = `
 Object {
   "docs": Array [
     Object {
-      "collapsed": true,
       "items": Array [
         Object {
           "id": "foo/bar",
@@ -202,7 +123,6 @@ Object {
       "type": "category",
     },
     Object {
-      "collapsed": true,
       "items": Array [
         Object {
           "id": "hello",
diff --git a/packages/docusaurus-plugin-content-docs/src/__tests__/__snapshots__/version.test.ts.snap b/packages/docusaurus-plugin-content-docs/src/__tests__/__snapshots__/version.test.ts.snap
index 26c10f3c0a..47ffaef77f 100644
--- a/packages/docusaurus-plugin-content-docs/src/__tests__/__snapshots__/version.test.ts.snap
+++ b/packages/docusaurus-plugin-content-docs/src/__tests__/__snapshots__/version.test.ts.snap
@@ -4,7 +4,6 @@ exports[`docsVersion first time versioning 1`] = `
 Object {
   "version-1.0.0/docs": Array [
     Object {
-      "collapsed": true,
       "items": Array [
         Object {
           "items": Array [
@@ -34,7 +33,6 @@ Object {
       "type": "category",
     },
     Object {
-      "collapsed": true,
       "items": Array [
         Object {
           "id": "version-1.0.0/hello",
@@ -52,7 +50,6 @@ exports[`docsVersion not the first time versioning 1`] = `
 Object {
   "version-2.0.0/docs": Array [
     Object {
-      "collapsed": true,
       "items": Array [
         Object {
           "id": "version-2.0.0/foo/bar",
@@ -63,7 +60,6 @@ Object {
       "type": "category",
     },
     Object {
-      "collapsed": true,
       "items": Array [
         Object {
           "id": "version-2.0.0/hello",
diff --git a/packages/docusaurus-plugin-content-docs/src/__tests__/sidebars.test.ts b/packages/docusaurus-plugin-content-docs/src/__tests__/sidebars.test.ts
index 11d882b22a..49a788dfd9 100644
--- a/packages/docusaurus-plugin-content-docs/src/__tests__/sidebars.test.ts
+++ b/packages/docusaurus-plugin-content-docs/src/__tests__/sidebars.test.ts
@@ -126,19 +126,4 @@ describe('loadSidebars', () => {
     const result = loadSidebars(null);
     expect(result).toEqual({});
   });
-
-  test('sidebars with category.collapsed property', async () => {
-    const sidebarPath = path.join(fixtureDir, 'sidebars-collapsed.json');
-    const result = loadSidebars([sidebarPath]);
-    expect(result).toMatchSnapshot();
-  });
-
-  test('sidebars with category.collapsed property at first level', async () => {
-    const sidebarPath = path.join(
-      fixtureDir,
-      'sidebars-collapsed-first-level.json',
-    );
-    const result = loadSidebars([sidebarPath]);
-    expect(result).toMatchSnapshot();
-  });
 });
diff --git a/packages/docusaurus-plugin-content-docs/src/sidebars.ts b/packages/docusaurus-plugin-content-docs/src/sidebars.ts
index abe988984b..cfe1b36254 100644
--- a/packages/docusaurus-plugin-content-docs/src/sidebars.ts
+++ b/packages/docusaurus-plugin-content-docs/src/sidebars.ts
@@ -33,7 +33,6 @@ function normalizeCategoryShorthand(
 ): SidebarItemCategoryRaw[] {
   return Object.entries(sidebar).map(([label, items]) => ({
     type: 'category',
-    collapsed: true,
     label,
     items,
   }));
@@ -57,7 +56,7 @@ function assertItem(item: Object, keys: string[]): void {
 }
 
 function assertIsCategory(item: any): asserts item is SidebarItemCategoryRaw {
-  assertItem(item, ['items', 'label', 'collapsed']);
+  assertItem(item, ['items', 'label']);
   if (typeof item.label !== 'string') {
     throw new Error(
       `Error loading ${JSON.stringify(item)}. "label" must be a string.`,
@@ -68,12 +67,6 @@ function assertIsCategory(item: any): asserts item is SidebarItemCategoryRaw {
       `Error loading ${JSON.stringify(item)}. "items" must be an array.`,
     );
   }
-  // "collapsed" is an optional property
-  if (item.hasOwnProperty('collapsed') && typeof item.collapsed !== 'boolean') {
-    throw new Error(
-      `Error loading ${JSON.stringify(item)}. "collapsed" must be a boolean.`,
-    );
-  }
 }
 
 function assertIsDoc(item: any): asserts item is SidebarItemDoc {
diff --git a/packages/docusaurus-plugin-content-docs/src/types.ts b/packages/docusaurus-plugin-content-docs/src/types.ts
index 9516cec3f7..4929797c59 100644
--- a/packages/docusaurus-plugin-content-docs/src/types.ts
+++ b/packages/docusaurus-plugin-content-docs/src/types.ts
@@ -40,14 +40,12 @@ export interface SidebarItemCategory {
   type: 'category';
   label: string;
   items: SidebarItem[];
-  collapsed?: boolean;
 }
 
 export interface SidebarItemCategoryRaw {
   type: 'category';
   label: string;
   items: SidebarItemRaw[];
-  collapsed?: boolean;
 }
 
 export type SidebarItem =
@@ -83,7 +81,6 @@ export interface DocsSidebarItemCategory {
   type: 'category';
   label: string;
   items: DocsSidebarItem[];
-  collapsed?: boolean;
 }
 
 export type DocsSidebarItem = SidebarItemLink | DocsSidebarItemCategory;
diff --git a/packages/docusaurus-theme-classic/src/theme/DocSidebar/index.js b/packages/docusaurus-theme-classic/src/theme/DocSidebar/index.js
index 29bdfa2b70..c59c3611f4 100644
--- a/packages/docusaurus-theme-classic/src/theme/DocSidebar/index.js
+++ b/packages/docusaurus-theme-classic/src/theme/DocSidebar/index.js
@@ -105,11 +105,8 @@ function mutateSidebarCollapsingState(item, path) {
         items
           .map((childItem) => mutateSidebarCollapsingState(childItem, path))
           .filter((val) => val).length > 0;
-      // only modify item.collapsed if there are child items active and the category collapsed is set to true
-      if (anyChildItemsActive && item.collapsed) {
-        // eslint-disable-next-line no-param-reassign
-        item.collapsed = !anyChildItemsActive;
-      }
+      // eslint-disable-next-line no-param-reassign
+      item.collapsed = !anyChildItemsActive;
       return anyChildItemsActive;
     }
 
diff --git a/website/docs/docs.md b/website/docs/docs.md
index b46a67309f..d44c89ebed 100644
--- a/website/docs/docs.md
+++ b/website/docs/docs.md
@@ -207,7 +207,6 @@ type SidebarItemCategory = {
   type: 'category';
   label: string; // Sidebar label text.
   items: SidebarItem[]; // Array of sidebar items.
-  collapsed: boolean; // Set the category to be collapsed or open by default
 };
 ```