diff --git a/docs/pages/material-ui/api/toggle-button-group.json b/docs/pages/material-ui/api/toggle-button-group.json
index e3d1c10eefb45c..add23c498c045e 100644
--- a/docs/pages/material-ui/api/toggle-button-group.json
+++ b/docs/pages/material-ui/api/toggle-button-group.json
@@ -81,6 +81,12 @@
       "description": "Styles applied to the children if `orientation=\"vertical\"`.",
       "isGlobal": false
     },
+    {
+      "key": "horizontal",
+      "className": "MuiToggleButtonGroup-horizontal",
+      "description": "Styles applied to the root element if `orientation=\"horizontal\"`.",
+      "isGlobal": false
+    },
     {
       "key": "lastButton",
       "className": "MuiToggleButtonGroup-lastButton",
@@ -99,6 +105,12 @@
       "description": "Styles applied to the root element.",
       "isGlobal": false
     },
+    {
+      "key": "selected",
+      "className": "Mui-selected",
+      "description": "State class applied to the root element if `selected={true}`.",
+      "isGlobal": true
+    },
     {
       "key": "vertical",
       "className": "MuiToggleButtonGroup-vertical",
diff --git a/docs/translations/api-docs/toggle-button-group/toggle-button-group.json b/docs/translations/api-docs/toggle-button-group/toggle-button-group.json
index 21eccbcd92b660..3e9c41ea144f5f 100644
--- a/docs/translations/api-docs/toggle-button-group/toggle-button-group.json
+++ b/docs/translations/api-docs/toggle-button-group/toggle-button-group.json
@@ -57,6 +57,11 @@
       "nodeName": "the children",
       "conditions": "<code>orientation=\"vertical\"</code>"
     },
+    "horizontal": {
+      "description": "Styles applied to {{nodeName}} if {{conditions}}.",
+      "nodeName": "the root element",
+      "conditions": "<code>orientation=\"horizontal\"</code>"
+    },
     "lastButton": {
       "description": "Styles applied to {{nodeName}}.",
       "nodeName": "the last button in the toggle button group"
@@ -66,6 +71,11 @@
       "nodeName": "buttons in the middle of the toggle button group"
     },
     "root": { "description": "Styles applied to the root element." },
+    "selected": {
+      "description": "State class applied to {{nodeName}} if {{conditions}}.",
+      "nodeName": "the root element",
+      "conditions": "<code>selected={true}</code>"
+    },
     "vertical": {
       "description": "Styles applied to {{nodeName}} if {{conditions}}.",
       "nodeName": "the root element",
diff --git a/packages/mui-material/src/ToggleButtonGroup/toggleButtonGroupClasses.ts b/packages/mui-material/src/ToggleButtonGroup/toggleButtonGroupClasses.ts
index 75cf854a4d59fc..9cb2f1cc7958a5 100644
--- a/packages/mui-material/src/ToggleButtonGroup/toggleButtonGroupClasses.ts
+++ b/packages/mui-material/src/ToggleButtonGroup/toggleButtonGroupClasses.ts
@@ -4,6 +4,10 @@ import generateUtilityClass from '@mui/utils/generateUtilityClass';
 export interface ToggleButtonGroupClasses {
   /** Styles applied to the root element. */
   root: string;
+  /** State class applied to the root element if `selected={true}`. */
+  selected: string;
+  /** Styles applied to the root element if `orientation="horizontal"`. */
+  horizontal: string;
   /** Styles applied to the root element if `orientation="vertical"`. */
   vertical: string;
   /** State class applied to the root element if `disabled={true}`. */
@@ -35,6 +39,7 @@ const toggleButtonGroupClasses: ToggleButtonGroupClasses = generateUtilityClasse
   [
     'root',
     'selected',
+    'horizontal',
     'vertical',
     'disabled',
     'grouped',