diff --git a/change/@fluentui-react-menu-11ee527c-b6cc-48eb-b8dd-b85a8d84ca09.json b/change/@fluentui-react-menu-11ee527c-b6cc-48eb-b8dd-b85a8d84ca09.json
new file mode 100644
index 0000000000000..8c0eda457cce6
--- /dev/null
+++ b/change/@fluentui-react-menu-11ee527c-b6cc-48eb-b8dd-b85a8d84ca09.json
@@ -0,0 +1,7 @@
+{
+  "type": "minor",
+  "comment": "Fix: Left arrow behavior in MenuGrid submenus",
+  "packageName": "@fluentui/react-menu",
+  "email": "email not defined",
+  "dependentChangeType": "patch"
+}
diff --git a/change/@fluentui-react-menu-grid-preview-785678f1-ead6-4795-bb56-a75f0d153668.json b/change/@fluentui-react-menu-grid-preview-785678f1-ead6-4795-bb56-a75f0d153668.json
new file mode 100644
index 0000000000000..6d4c8208da6c4
--- /dev/null
+++ b/change/@fluentui-react-menu-grid-preview-785678f1-ead6-4795-bb56-a75f0d153668.json
@@ -0,0 +1,7 @@
+{
+  "type": "minor",
+  "comment": "Fix: Left arrow behavior in MenuGrid submenus",
+  "packageName": "@fluentui/react-menu-grid-preview",
+  "email": "email not defined",
+  "dependentChangeType": "patch"
+}
diff --git a/packages/react-components/react-menu-grid-preview/library/src/components/MenuGrid/MenuGrid.cy.tsx b/packages/react-components/react-menu-grid-preview/library/src/components/MenuGrid/MenuGrid.cy.tsx
index 097503f772d7c..685959ad1f79d 100644
--- a/packages/react-components/react-menu-grid-preview/library/src/components/MenuGrid/MenuGrid.cy.tsx
+++ b/packages/react-components/react-menu-grid-preview/library/src/components/MenuGrid/MenuGrid.cy.tsx
@@ -308,4 +308,12 @@ describe('With MenuList submenus', () => {
     cy.get(menuSelector).should('have.length', 1);
     cy.focused().should('have.attr', 'role', 'menuitem');
   });
+
+  it('should not close submenu when pressing ArrowLeft inside it', () => {
+    mount(<WithSubmenuExample />);
+    cy.get(menuGridItemSelector).first().focus().realPress('ArrowRight').realPress('Enter');
+    cy.get(menuSelector).should('have.length', 1);
+    cy.focused().should('have.attr', 'role', 'menuitem').realPress('ArrowLeft');
+    cy.get(menuSelector).should('have.length', 1);
+  });
 });
diff --git a/packages/react-components/react-menu-grid-preview/library/src/components/MenuGrid/useMenuGrid.test.ts b/packages/react-components/react-menu-grid-preview/library/src/components/MenuGrid/useMenuGrid.test.ts
index 2100a83032585..711f41d78441a 100644
--- a/packages/react-components/react-menu-grid-preview/library/src/components/MenuGrid/useMenuGrid.test.ts
+++ b/packages/react-components/react-menu-grid-preview/library/src/components/MenuGrid/useMenuGrid.test.ts
@@ -22,11 +22,11 @@ describe('useMenuGrid_unstable', () => {
 
     beforeEach(() => {
       rows = [
-        { textContent: 'Apple', focus: jest.fn(), hasAttribute: () => true, getAttribute: () => 'row' },
-        { textContent: 'Banana', focus: jest.fn(), hasAttribute: () => true, getAttribute: () => 'row' },
-        { textContent: 'Cherry', focus: jest.fn(), hasAttribute: () => true, getAttribute: () => 'row' },
-        { textContent: 'Apricot', focus: jest.fn(), hasAttribute: () => true, getAttribute: () => 'row' },
-        { textContent: 'Date', focus: jest.fn(), hasAttribute: () => true, getAttribute: () => 'row' },
+        { textContent: 'Apple', focus: jest.fn(), role: 'row' },
+        { textContent: 'Banana', focus: jest.fn(), role: 'row' },
+        { textContent: 'Cherry', focus: jest.fn(), role: 'row' },
+        { textContent: 'Apricot', focus: jest.fn(), role: 'row' },
+        { textContent: 'Date', focus: jest.fn(), role: 'row' },
       ];
 
       (useFocusFinders as jest.Mock).mockReturnValue({
@@ -37,7 +37,7 @@ describe('useMenuGrid_unstable', () => {
     const createEvent = (key: string, target?: Record<string, unknown>): React.KeyboardEvent<HTMLElement> =>
       ({
         key,
-        target: target ?? { hasAttribute: () => true, getAttribute: () => 'row' },
+        target: target ?? { role: 'row' },
       } as unknown as React.KeyboardEvent<HTMLElement>);
 
     it('should focus the next row matching the pressed character', () => {
@@ -97,7 +97,7 @@ describe('useMenuGrid_unstable', () => {
 
     it('should not apply first-letter navigation when event target is not a row', () => {
       const current = rows[0]; // Apple
-      const nonRowTarget = { hasAttribute: () => true, getAttribute: () => 'gridcell' };
+      const nonRowTarget = { role: 'gridcell' };
 
       const { result } = renderHook(() => useMenuGrid_unstable({}, React.createRef()));
       (result.current.root.ref as React.RefCallback<HTMLElement>)?.(document.createElement('div'));
diff --git a/packages/react-components/react-menu-grid-preview/library/src/components/MenuGrid/useMenuGrid.ts b/packages/react-components/react-menu-grid-preview/library/src/components/MenuGrid/useMenuGrid.ts
index dda14d5a5e0bd..97fd7056fca84 100644
--- a/packages/react-components/react-menu-grid-preview/library/src/components/MenuGrid/useMenuGrid.ts
+++ b/packages/react-components/react-menu-grid-preview/library/src/components/MenuGrid/useMenuGrid.ts
@@ -56,14 +56,11 @@ export const useMenuGrid_unstable = (props: MenuGridProps, ref: React.Ref<HTMLDi
       const target = e.target as HTMLElement;
 
       // Only apply first-letter navigation when event target is a grid row, otherwise it may conflict with other components inside the grid row
-      if (!target.hasAttribute('role') || target.getAttribute('role') !== 'row') {
+      if (target.role !== 'row') {
         return;
       }
 
-      const rows = findAllFocusable(
-        innerRef.current,
-        (el: HTMLElement) => el.hasAttribute('role') && el.getAttribute('role') === 'row',
-      );
+      const rows = findAllFocusable(innerRef.current, (el: HTMLElement) => el.role === 'row');
 
       let startIndex = rows.indexOf(itemEl) + 1;
       if (startIndex === rows.length) {
diff --git a/packages/react-components/react-menu-grid-preview/library/src/components/MenuGrid/useMenuGridContextValues.ts b/packages/react-components/react-menu-grid-preview/library/src/components/MenuGrid/useMenuGridContextValues.ts
index 19d7efea7b0c0..0bcccedfce442 100644
--- a/packages/react-components/react-menu-grid-preview/library/src/components/MenuGrid/useMenuGridContextValues.ts
+++ b/packages/react-components/react-menu-grid-preview/library/src/components/MenuGrid/useMenuGridContextValues.ts
@@ -8,6 +8,7 @@ const menuList = {
   hasIcons: false,
   hasCheckmarks: false,
   shouldOpenOnArrowRight: false,
+  shouldCloseOnArrowLeft: false,
 };
 
 export function useMenuGridContextValues_unstable(state: MenuGridState): MenuGridContextValues {
diff --git a/packages/react-components/react-menu/library/etc/react-menu.api.md b/packages/react-components/react-menu/library/etc/react-menu.api.md
index fb505122c31a3..3cfd08cfe69df 100644
--- a/packages/react-components/react-menu/library/etc/react-menu.api.md
+++ b/packages/react-components/react-menu/library/etc/react-menu.api.md
@@ -231,6 +231,7 @@ export type MenuListContextValue = Pick<MenuListProps, 'checkedValues' | 'hasIco
     selectRadio?: SelectableHandler;
     onCheckedValueChange?: (e: MenuCheckedValueChangeEvent, data: MenuCheckedValueChangeData) => void;
     shouldOpenOnArrowRight?: boolean;
+    shouldCloseOnArrowLeft?: boolean;
 };
 
 // @public (undocumented)
diff --git a/packages/react-components/react-menu/library/src/components/MenuPopover/useMenuPopover.ts b/packages/react-components/react-menu/library/src/components/MenuPopover/useMenuPopover.ts
index 70819a0ce1772..bd1a12031efc5 100644
--- a/packages/react-components/react-menu/library/src/components/MenuPopover/useMenuPopover.ts
+++ b/packages/react-components/react-menu/library/src/components/MenuPopover/useMenuPopover.ts
@@ -8,6 +8,7 @@ import { getIntrinsicElementProps, useEventCallback, useMergedRefs, slot, useTim
 import * as React from 'react';
 
 import { useMenuContext_unstable } from '../../contexts/menuContext';
+import { useMenuListContext_unstable } from '../../contexts/menuListContext';
 import { dispatchMenuEnterEvent, useIsSubmenu } from '../../utils/index';
 import { MenuPopoverProps, MenuPopoverState } from './MenuPopover.types';
 
@@ -31,6 +32,8 @@ export const useMenuPopover_unstable = (props: MenuPopoverProps, ref: React.Ref<
   const triggerRef = useMenuContext_unstable(context => context.triggerRef);
 
   const isSubmenu = useIsSubmenu();
+  const shouldCloseOnArrowLeft = useMenuListContext_unstable(ctx => ctx.shouldCloseOnArrowLeft ?? true);
+
   const canDispatchCustomEventRef = React.useRef(true);
   const restoreFocusSourceAttributes = useRestoreFocusSource();
   const [setThrottleTimeout, clearThrottleTimeout] = useTimeout();
@@ -93,7 +96,7 @@ export const useMenuPopover_unstable = (props: MenuPopoverProps, ref: React.Ref<
   });
   rootProps.onKeyDown = useEventCallback((event: React.KeyboardEvent<HTMLDivElement>) => {
     const key = event.key;
-    if (key === Escape || (isSubmenu && key === CloseArrowKey)) {
+    if (key === Escape || (isSubmenu && shouldCloseOnArrowLeft && key === CloseArrowKey)) {
       if (open && popoverRef.current?.contains(event.target as HTMLElement) && !event.isDefaultPrevented()) {
         setOpen(event, { open: false, keyboard: true, type: 'menuPopoverKeyDown', event });
         // stop propagation to avoid conflicting with other elements that listen for `Escape`
diff --git a/packages/react-components/react-menu/library/src/contexts/menuListContext.tsx b/packages/react-components/react-menu/library/src/contexts/menuListContext.tsx
index 4274fc8d9e61a..8d1e6020fccba 100644
--- a/packages/react-components/react-menu/library/src/contexts/menuListContext.tsx
+++ b/packages/react-components/react-menu/library/src/contexts/menuListContext.tsx
@@ -44,6 +44,14 @@ export type MenuListContextValue = Pick<MenuListProps, 'checkedValues' | 'hasIco
    * @default true
    */
   shouldOpenOnArrowRight?: boolean;
+  /**
+   * Whether child menus (submenus) should close when the user presses the ArrowLeft key.
+   * Set to `false` when the list context is provided by a grid-like container (e.g. MenuGrid) where
+   * ArrowLeft is reserved for column navigation.
+   *
+   * @default true
+   */
+  shouldCloseOnArrowLeft?: boolean;
 };
 
 export const MenuListProvider = MenuListContext.Provider;