diff --git a/services/core/java/com/android/server/wm/ActivityRecord.java b/services/core/java/com/android/server/wm/ActivityRecord.java
index 2b2100e56f443..3b4429846c1e0 100644
--- a/services/core/java/com/android/server/wm/ActivityRecord.java
+++ b/services/core/java/com/android/server/wm/ActivityRecord.java
@@ -223,6 +223,7 @@ import static com.android.server.wm.ActivityTaskSupervisor.PRESERVE_WINDOWS;
 import static com.android.server.wm.IdentifierProto.HASH_CODE;
 import static com.android.server.wm.IdentifierProto.TITLE;
 import static com.android.server.wm.IdentifierProto.USER_ID;
+import static com.android.server.wm.LetterboxConfiguration.DEFAULT_LETTERBOX_ASPECT_RATIO_FOR_MULTI_WINDOW;
 import static com.android.server.wm.LetterboxConfiguration.MIN_FIXED_ORIENTATION_LETTERBOX_ASPECT_RATIO;
 import static com.android.server.wm.SurfaceAnimator.ANIMATION_TYPE_APP_TRANSITION;
 import static com.android.server.wm.SurfaceAnimator.ANIMATION_TYPE_RECENTS;
@@ -8785,9 +8786,18 @@ final class ActivityRecord extends WindowToken implements WindowManagerService.A
 
         final float letterboxAspectRatioOverride =
                 mLetterboxUiController.getFixedOrientationLetterboxAspectRatio(newParentConfig);
-        final float desiredAspectRatio =
-                letterboxAspectRatioOverride > MIN_FIXED_ORIENTATION_LETTERBOX_ASPECT_RATIO
-                        ? letterboxAspectRatioOverride : computeAspectRatio(parentBounds);
+
+        // Aspect ratio as suggested by the system. Apps requested mix/max aspect ratio will
+        // be respected in #applyAspectRatio.
+        final float desiredAspectRatio;
+        if (isDefaultMultiWindowLetterboxAspectRatioDesired(newParentConfig)) {
+            desiredAspectRatio = DEFAULT_LETTERBOX_ASPECT_RATIO_FOR_MULTI_WINDOW;
+        } else if (letterboxAspectRatioOverride > MIN_FIXED_ORIENTATION_LETTERBOX_ASPECT_RATIO) {
+            desiredAspectRatio = letterboxAspectRatioOverride;
+        } else {
+            desiredAspectRatio = computeAspectRatio(parentBounds);
+        }
+
         // Apply aspect ratio to resolved bounds
         mIsAspectRatioApplied = applyAspectRatio(resolvedBounds, containingBoundsWithInsets,
                 containingBounds, desiredAspectRatio);
@@ -8812,6 +8822,20 @@ final class ActivityRecord extends WindowToken implements WindowManagerService.A
         mLetterboxBoundsForFixedOrientationAndAspectRatio = new Rect(resolvedBounds);
     }
 
+    /**
+     * Returns {@code true} if the default aspect ratio for a letterboxed app in multi-window mode
+     * should be used.
+     */
+    private boolean isDefaultMultiWindowLetterboxAspectRatioDesired(
+            @NonNull Configuration parentConfig) {
+        if (mDisplayContent == null) {
+            return false;
+        }
+        final int windowingMode = parentConfig.windowConfiguration.getWindowingMode();
+        return WindowConfiguration.inMultiWindowMode(windowingMode)
+                && !mDisplayContent.getIgnoreOrientationRequest();
+    }
+
     /**
      * Resolves aspect ratio restrictions for an activity. If the bounds are restricted by
      * aspect ratio, the position will be adjusted later in {@link #updateResolvedBoundsPosition
diff --git a/services/core/java/com/android/server/wm/LetterboxConfiguration.java b/services/core/java/com/android/server/wm/LetterboxConfiguration.java
index a93cb8ad2d974..067a18c88aaa6 100644
--- a/services/core/java/com/android/server/wm/LetterboxConfiguration.java
+++ b/services/core/java/com/android/server/wm/LetterboxConfiguration.java
@@ -52,6 +52,9 @@ final class LetterboxConfiguration {
      */
     static final float MIN_FIXED_ORIENTATION_LETTERBOX_ASPECT_RATIO = 1.0f;
 
+    /** The default aspect ratio for a letterboxed app in multi-window mode. */
+    static final float DEFAULT_LETTERBOX_ASPECT_RATIO_FOR_MULTI_WINDOW = 1.01f;
+
     /** Letterboxed app window position multiplier indicating center position. */
     static final float LETTERBOX_POSITION_MULTIPLIER_CENTER = 0.5f;
 
diff --git a/services/tests/wmtests/src/com/android/server/wm/SizeCompatTests.java b/services/tests/wmtests/src/com/android/server/wm/SizeCompatTests.java
index 2dd34eb5ac4d7..28fcb12f2bcad 100644
--- a/services/tests/wmtests/src/com/android/server/wm/SizeCompatTests.java
+++ b/services/tests/wmtests/src/com/android/server/wm/SizeCompatTests.java
@@ -2046,6 +2046,72 @@ public class SizeCompatTests extends WindowTestsBase {
                 activityBounds.width());
     }
 
+    @Test
+    public void testDefaultLetterboxAspectRatioForMultiWindowMode_fixedOrientationApp() {
+        // Set-up display in portrait.
+        mAtm.mDevEnableNonResizableMultiWindow = true;
+        final int screenWidth = 1100;
+        final int screenHeight = 2100;
+        setUpDisplaySizeWithApp(screenWidth, screenHeight);
+
+        mActivity.mDisplayContent.getWindowConfiguration()
+                .setAppBounds(/* left */ 0, /* top */ 0, screenWidth, screenHeight);
+
+        final TestSplitOrganizer organizer =
+                new TestSplitOrganizer(mAtm, mActivity.getDisplayContent());
+        // Move activity to multi-window which takes half of the screen.
+        mTask.reparent(organizer.mPrimary, POSITION_TOP, /* moveParents= */ false , "test");
+        organizer.mPrimary.setBounds(0, 0, screenWidth, getExpectedSplitSize(screenHeight));
+        assertEquals(WINDOWING_MODE_MULTI_WINDOW, mTask.getWindowingMode());
+        assertEquals(WINDOWING_MODE_MULTI_WINDOW, mActivity.getWindowingMode());
+
+        // Unresizable portrait-only activity.
+        prepareUnresizable(mActivity, SCREEN_ORIENTATION_PORTRAIT);
+
+        // Activity should be letterboxed with an aspect ratio of 1.01.
+        final Rect afterBounds = mActivity.getBounds();
+        final float actualAspectRatio = 1f * afterBounds.height() / afterBounds.width();
+        assertEquals(LetterboxConfiguration.DEFAULT_LETTERBOX_ASPECT_RATIO_FOR_MULTI_WINDOW,
+                actualAspectRatio, 0.001f);
+        assertTrue(mActivity.areBoundsLetterboxed());
+    }
+
+    @Test
+    public void
+            testDefaultLetterboxAspectRatioForMultiWindowMode_fixedOrientationAppWithMinRatio() {
+        // Set-up display in portrait.
+        mAtm.mDevEnableNonResizableMultiWindow = true;
+        final int screenWidth = 1100;
+        final int screenHeight = 2100;
+        setUpDisplaySizeWithApp(screenWidth, screenHeight);
+
+        mActivity.mDisplayContent.getWindowConfiguration()
+                .setAppBounds(/* left */ 0, /* top */ 0, screenWidth, screenHeight);
+
+        // Set min aspect ratio to value greater than the default letterbox aspect ratio for
+        // multi-window mode.
+        final float minAspectRatio = 1.2f;
+        mActivity.info.setMinAspectRatio(minAspectRatio);
+
+        final TestSplitOrganizer organizer =
+                new TestSplitOrganizer(mAtm, mActivity.getDisplayContent());
+        // Move activity to multi-window which takes half of the screen.
+        mTask.reparent(organizer.mPrimary, POSITION_TOP, /* moveParents= */ false , "test");
+        organizer.mPrimary.setBounds(0, 0, screenWidth, getExpectedSplitSize(screenHeight));
+        assertEquals(WINDOWING_MODE_MULTI_WINDOW, mTask.getWindowingMode());
+        assertEquals(WINDOWING_MODE_MULTI_WINDOW, mActivity.getWindowingMode());
+
+        // Unresizable portrait-only activity.
+        prepareUnresizable(mActivity, SCREEN_ORIENTATION_PORTRAIT);
+
+        // Activity should be letterboxed with the min aspect ratio requested by the app NOT the
+        // default letterbox aspect ratio for multi-window.
+        final Rect afterBounds = mActivity.getBounds();
+        final float actualAspectRatio = 1f * afterBounds.height() / afterBounds.width();
+        assertEquals(minAspectRatio, actualAspectRatio, 0.001f);
+        assertTrue(mActivity.areBoundsLetterboxed());
+    }
+
     @Test
     public void testDisplayIgnoreOrientationRequest_unresizableWithCorrespondingMinAspectRatio() {
         // Set up a display in landscape and ignoring orientation request.