diff --git a/packages/eui/src/components/flyout/use_flyout_resizable.test.ts b/packages/eui/src/components/flyout/use_flyout_resizable.test.ts
new file mode 100644
index 00000000000..4d0e5c8255a
--- /dev/null
+++ b/packages/eui/src/components/flyout/use_flyout_resizable.test.ts
@@ -0,0 +1,140 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0 and the Server Side Public License, v 1; you may not use this file except
+ * in compliance with, at your election, the Elastic License 2.0 or the Server
+ * Side Public License, v 1.
+ */
+
+import { renderHook, act, waitFor } from '@testing-library/react';
+import { useEuiFlyoutResizable } from './use_flyout_resizable';
+
+describe('useEuiFlyoutResizable', () => {
+  const mockProps = {
+    enabled: false,
+    minWidth: 200,
+    maxWidth: 1000,
+    onResize: jest.fn(),
+    side: 'right' as const,
+    size: '50vw',
+  };
+
+  // Mock DOM element with offsetWidth
+  const createMockElement = (offsetWidth = 600) =>
+    ({ offsetWidth, style: { direction: 'ltr' } } as HTMLElement);
+
+  beforeEach(() => {
+    jest.clearAllMocks();
+
+    // Mock window.innerWidth for getFlyoutMinMaxWidth calculations
+    Object.defineProperty(window, 'innerWidth', {
+      writable: true,
+      configurable: true,
+      value: 1200,
+    });
+
+    // Mock getComputedStyle
+    jest.spyOn(window, 'getComputedStyle').mockReturnValue({
+      direction: 'ltr',
+    } as CSSStyleDeclaration);
+  });
+
+  it('should not measure flyout width when disabled', () => {
+    const { result } = renderHook(() =>
+      useEuiFlyoutResizable({
+        ...mockProps,
+        enabled: false,
+        size: '50vw',
+      })
+    );
+
+    const mockElement = createMockElement(600);
+
+    // Set the flyout ref (this would normally trigger measurement)
+    act(() => {
+      result.current.setFlyoutRef(mockElement);
+    });
+
+    // Should return the original responsive size, not a measured pixel value
+    expect(result.current.size).toBe('50vw');
+  });
+
+  it('should return original size instead of measured width when disabled', async () => {
+    const { result, rerender } = renderHook(
+      (props) => useEuiFlyoutResizable(props),
+      {
+        initialProps: {
+          ...mockProps,
+          enabled: true,
+          size: '50vw',
+        },
+      }
+    );
+
+    const mockElement = createMockElement(600);
+
+    // Set the flyout ref while enabled (this should measure the width)
+    act(() => {
+      result.current.setFlyoutRef(mockElement);
+    });
+
+    // Wait for the useEffect to run and measure the width
+    await waitFor(() => {
+      expect(result.current.size).toBe(600);
+    });
+
+    // Now disable resizing with a different size
+    rerender({
+      ...mockProps,
+      enabled: false,
+      size: '400px',
+    });
+
+    // Should return original size, not the previously measured width
+    expect(result.current.size).toBe('400px');
+  });
+
+  it('should not update flyout width when size changes while disabled', () => {
+    const { result, rerender } = renderHook(
+      (props) => useEuiFlyoutResizable(props),
+      {
+        initialProps: {
+          ...mockProps,
+          enabled: false,
+          size: 300,
+        },
+      }
+    );
+
+    const mockElement = createMockElement(600);
+    act(() => {
+      result.current.setFlyoutRef(mockElement);
+    });
+
+    // Should return original size
+    expect(result.current.size).toBe(300);
+
+    // Change the size while disabled
+    rerender({
+      ...mockProps,
+      enabled: false,
+      size: 500,
+    });
+
+    // Should return the new original size, not trigger any measurement
+    expect(result.current.size).toBe(500);
+  });
+
+  it('should return original size when enabled but not measured yet', () => {
+    const { result } = renderHook(() =>
+      useEuiFlyoutResizable({
+        ...mockProps,
+        enabled: true,
+        size: 400,
+      })
+    );
+
+    // When enabled but no flyout width measured yet, should return original size
+    expect(result.current.size).toBe(400);
+  });
+});
diff --git a/packages/eui/src/components/flyout/use_flyout_resizable.ts b/packages/eui/src/components/flyout/use_flyout_resizable.ts
index d931788ecb5..1dba4f25aeb 100644
--- a/packages/eui/src/components/flyout/use_flyout_resizable.ts
+++ b/packages/eui/src/components/flyout/use_flyout_resizable.ts
@@ -56,18 +56,20 @@ export const useEuiFlyoutResizable = ({
   const [flyoutRef, setFlyoutRef] = useState<HTMLElement | null>(null);
 
   useEffect(() => {
+    if (!enabled) return; // Don't measure when resizing is disabled
     if (!flyoutWidth && flyoutRef) {
       setCallOnResize(false); // Don't call `onResize` for non-user width changes
       setFlyoutWidth(getFlyoutMinMaxWidth(flyoutRef.offsetWidth));
     }
-  }, [flyoutWidth, flyoutRef, getFlyoutMinMaxWidth]);
+  }, [flyoutWidth, flyoutRef, getFlyoutMinMaxWidth, enabled]);
 
   // Update flyout width when consumers pass in a new `size`
   useEffect(() => {
+    if (!enabled) return; // Don't update width when resizing is disabled
     setCallOnResize(false);
     // For string `size`s, resetting flyoutWidth to 0 will trigger the above useEffect's recalculation
     setFlyoutWidth(typeof _size === 'number' ? getFlyoutMinMaxWidth(_size) : 0);
-  }, [_size, getFlyoutMinMaxWidth]);
+  }, [_size, getFlyoutMinMaxWidth, enabled]);
 
   // Initial numbers to calculate from, on resize drag start
   const initialWidth = useRef(0);
@@ -169,7 +171,10 @@ export const useEuiFlyoutResizable = ({
     }
   }, [onResize, callOnResize, flyoutWidth, enabled]);
 
-  const size = useMemo(() => flyoutWidth || _size, [flyoutWidth, _size]);
+  const size = useMemo(
+    () => (enabled ? flyoutWidth || _size : _size),
+    [enabled, flyoutWidth, _size]
+  );
 
   return {
     onKeyDown,