diff --git a/quickstep/res/values/colors.xml b/quickstep/res/values/colors.xml
index 1b5b0ee..14a916f 100644
--- a/quickstep/res/values/colors.xml
+++ b/quickstep/res/values/colors.xml
@@ -31,6 +31,7 @@
     <color name="taskbar_nav_icon_dark_color_on_home">#99000000</color>
     <color name="taskbar_stashed_handle_light_color">#EBffffff</color>
     <color name="taskbar_stashed_handle_dark_color">#99000000</color>
+    <color name="taskbar_running_app_indicator_color">#646464</color>
 
     <!-- Floating rotation button -->
     <color name="floating_rotation_button_light_color">#ffffff</color>
diff --git a/quickstep/res/values/dimens.xml b/quickstep/res/values/dimens.xml
index dbf075c..b862d7c 100644
--- a/quickstep/res/values/dimens.xml
+++ b/quickstep/res/values/dimens.xml
@@ -353,6 +353,9 @@
     <dimen name="taskbar_back_button_suw_start_margin">48dp</dimen>
     <dimen name="taskbar_back_button_suw_bottom_margin">1dp</dimen>
     <dimen name="taskbar_back_button_suw_height">72dp</dimen>
+    <dimen name="taskbar_running_app_indicator_height">4dp</dimen>
+    <dimen name="taskbar_running_app_indicator_width">14dp</dimen>
+    <dimen name="taskbar_running_app_indicator_top_margin">2dp</dimen>
 
     <!-- Transient taskbar -->
     <dimen name="transient_taskbar_padding">12dp</dimen>
diff --git a/quickstep/src/com/android/launcher3/taskbar/DesktopTaskbarRunningAppsController.kt b/quickstep/src/com/android/launcher3/taskbar/DesktopTaskbarRunningAppsController.kt
index f665e21..06d25a2 100644
--- a/quickstep/src/com/android/launcher3/taskbar/DesktopTaskbarRunningAppsController.kt
+++ b/quickstep/src/com/android/launcher3/taskbar/DesktopTaskbarRunningAppsController.kt
@@ -80,6 +80,13 @@
         return newHotseatItemInfos.toTypedArray()
     }
 
+    override fun getRunningApps(): Set<String> {
+        if (!isInDesktopMode) {
+            return emptySet()
+        }
+        return allRunningDesktopAppInfos?.mapNotNull { it.targetPackage }?.toSet() ?: emptySet()
+    }
+
     @VisibleForTesting
     public override fun updateRunningApps(hotseatItems: SparseArray<ItemInfo>?) {
         if (!isInDesktopMode) {
diff --git a/quickstep/src/com/android/launcher3/taskbar/TaskbarModelCallbacks.java b/quickstep/src/com/android/launcher3/taskbar/TaskbarModelCallbacks.java
index 6c84f80..be87cfd 100644
--- a/quickstep/src/com/android/launcher3/taskbar/TaskbarModelCallbacks.java
+++ b/quickstep/src/com/android/launcher3/taskbar/TaskbarModelCallbacks.java
@@ -47,6 +47,7 @@
 import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
+import java.util.Set;
 import java.util.function.Predicate;
 
 /**
@@ -233,15 +234,23 @@
         }
         hotseatItemInfos = mControllers.taskbarRecentAppsController
                 .updateHotseatItemInfos(hotseatItemInfos);
+        Set<String> runningPackages = mControllers.taskbarRecentAppsController.getRunningApps();
 
         if (mDeferUpdatesForSUW) {
             ItemInfo[] finalHotseatItemInfos = hotseatItemInfos;
-            mDeferredUpdates = () -> mContainer.updateHotseatItems(finalHotseatItemInfos);
+            mDeferredUpdates = () ->
+                    commitHotseatItemUpdates(finalHotseatItemInfos, runningPackages);
         } else {
-            mContainer.updateHotseatItems(hotseatItemInfos);
+            commitHotseatItemUpdates(hotseatItemInfos, runningPackages);
         }
     }
 
+    private void commitHotseatItemUpdates(
+            ItemInfo[] hotseatItemInfos, Set<String> runningPackages) {
+        mContainer.updateHotseatItems(hotseatItemInfos);
+        mControllers.taskbarViewController.updateIconViewsRunningStates(runningPackages);
+    }
+
     /**
      * This is used to defer UI updates after SUW builds the unstash animation.
      * @param defer if true, defers updates to the UI
diff --git a/quickstep/src/com/android/launcher3/taskbar/TaskbarRecentAppsController.java b/quickstep/src/com/android/launcher3/taskbar/TaskbarRecentAppsController.java
index 8445cff..9b84f1b 100644
--- a/quickstep/src/com/android/launcher3/taskbar/TaskbarRecentAppsController.java
+++ b/quickstep/src/com/android/launcher3/taskbar/TaskbarRecentAppsController.java
@@ -15,6 +15,8 @@
  */
 package com.android.launcher3.taskbar;
 
+import static java.util.Collections.emptySet;
+
 import android.util.SparseArray;
 
 import androidx.annotation.CallSuper;
@@ -22,6 +24,8 @@
 import com.android.launcher3.model.data.AppInfo;
 import com.android.launcher3.model.data.ItemInfo;
 
+import java.util.Set;
+
 /**
  * Base class for providing recent apps functionality
  */
@@ -43,7 +47,8 @@
     }
 
     /** Stores the current {@link AppInfo} instances, no-op except in desktop environment. */
-    protected void setApps(AppInfo[] apps) { }
+    protected void setApps(AppInfo[] apps) {
+    }
 
     /**
      * Indicates whether recent apps functionality is enabled, should return false except in
@@ -59,5 +64,11 @@
     }
 
     /** Called to update the list of currently running apps, no-op except in desktop environment. */
-    protected void updateRunningApps(SparseArray<ItemInfo> hotseatItems) { }
+    protected void updateRunningApps(SparseArray<ItemInfo> hotseatItems) {
+    }
+
+    /** Returns the currently running apps, or an empty Set if outside of Desktop environment. */
+    public Set<String> getRunningApps() {
+        return emptySet();
+    }
 }
diff --git a/quickstep/src/com/android/launcher3/taskbar/TaskbarViewController.java b/quickstep/src/com/android/launcher3/taskbar/TaskbarViewController.java
index 5d0eac3..e0b446e 100644
--- a/quickstep/src/com/android/launcher3/taskbar/TaskbarViewController.java
+++ b/quickstep/src/com/android/launcher3/taskbar/TaskbarViewController.java
@@ -71,6 +71,7 @@
 import com.android.launcher3.views.IconButtonView;
 
 import java.io.PrintWriter;
+import java.util.Set;
 import java.util.function.Predicate;
 
 /**
@@ -507,6 +508,15 @@
         return mTaskbarView.getTaskbarDividerView();
     }
 
+    /** Updates which icons are marked as running given the Set of currently running packages. */
+    public void updateIconViewsRunningStates(Set<String> runningPackages) {
+        for (View iconView : getIconViews()) {
+            if (iconView instanceof BubbleTextView btv) {
+                btv.updateRunningState(runningPackages.contains(btv.getTargetPackageName()));
+            }
+        }
+    }
+
     /**
      * Defers any updates to the UI for the setup wizard animation.
      */
diff --git a/quickstep/tests/src/com/android/launcher3/taskbar/DesktopTaskbarRunningAppsControllerTest.kt b/quickstep/tests/src/com/android/launcher3/taskbar/DesktopTaskbarRunningAppsControllerTest.kt
index 93eefe2..2cfcf38 100644
--- a/quickstep/tests/src/com/android/launcher3/taskbar/DesktopTaskbarRunningAppsControllerTest.kt
+++ b/quickstep/tests/src/com/android/launcher3/taskbar/DesktopTaskbarRunningAppsControllerTest.kt
@@ -154,6 +154,29 @@
         assertThat(newHotseatItems?.map { it.targetPackage }).isEqualTo(expectedPackages)
     }
 
+    @Test
+    fun getRunningApps_notInDesktopMode_returnsEmptySet() {
+        setInDesktopMode(false)
+        val runningTasks =
+            createDesktopTasksFromPackageNames(listOf(RUNNING_APP_PACKAGE_1, RUNNING_APP_PACKAGE_2))
+        whenever(mockRecentsModel.runningTasks).thenReturn(runningTasks)
+        taskbarRunningAppsController.updateRunningApps(createSparseArray(emptyList()))
+
+        assertThat(taskbarRunningAppsController.runningApps).isEqualTo(emptySet<String>())
+    }
+
+    @Test
+    fun getRunningApps_inDesktopMode_returnsRunningApps() {
+        setInDesktopMode(true)
+        val runningTasks =
+            createDesktopTasksFromPackageNames(listOf(RUNNING_APP_PACKAGE_1, RUNNING_APP_PACKAGE_2))
+        whenever(mockRecentsModel.runningTasks).thenReturn(runningTasks)
+        taskbarRunningAppsController.updateRunningApps(createSparseArray(emptyList()))
+
+        assertThat(taskbarRunningAppsController.runningApps)
+            .isEqualTo(setOf(RUNNING_APP_PACKAGE_1, RUNNING_APP_PACKAGE_2))
+    }
+
     private fun createHotseatItemsFromPackageNames(packageNames: List<String>): List<ItemInfo> {
         return packageNames.map { createTestAppInfo(packageName = it) }
     }
diff --git a/res/values/colors.xml b/res/values/colors.xml
index a620eb0..dfe40fc 100644
--- a/res/values/colors.xml
+++ b/res/values/colors.xml
@@ -90,6 +90,8 @@
     <color name="drop_target_hover_button_color_light">#D3E3FD</color>
     <color name="drop_target_hover_button_color_dark">#0842A0</color>
 
+    <color name="taskbar_running_app_indicator_color">#000000</color>
+
     <color name="preload_icon_accent_color_light">#00668B</color>
     <color name="preload_icon_background_color_light">#B5CAD7</color>
     <color name="preload_icon_accent_color_dark">#4BB6E8</color>
diff --git a/res/values/dimens.xml b/res/values/dimens.xml
index 31def04..1bf59e8 100644
--- a/res/values/dimens.xml
+++ b/res/values/dimens.xml
@@ -394,6 +394,9 @@
     <dimen name="min_hotseat_icon_space">18dp</dimen>
     <dimen name="max_hotseat_icon_space">50dp</dimen>
     <dimen name="min_hotseat_qsb_width">0dp</dimen>
+    <dimen name="taskbar_running_app_indicator_height">0dp</dimen>
+    <dimen name="taskbar_running_app_indicator_width">0dp</dimen>
+    <dimen name="taskbar_running_app_indicator_top_margin">0dp</dimen>
 
     <!-- Transient taskbar (placeholders to compile in Launcher3 without Quickstep) -->
     <dimen name="transient_taskbar_padding">0dp</dimen>
diff --git a/src/com/android/launcher3/BubbleTextView.java b/src/com/android/launcher3/BubbleTextView.java
index 83236d1..7f316e2 100644
--- a/src/com/android/launcher3/BubbleTextView.java
+++ b/src/com/android/launcher3/BubbleTextView.java
@@ -46,6 +46,7 @@
 import android.text.TextUtils.TruncateAt;
 import android.util.AttributeSet;
 import android.util.Property;
+import android.util.Size;
 import android.util.TypedValue;
 import android.view.KeyEvent;
 import android.view.MotionEvent;
@@ -182,6 +183,13 @@
     private Animator mDotScaleAnim;
     private boolean mForceHideDot;
 
+    // These fields, related to showing running apps, are only used for Taskbar.
+    private final Size mRunningAppIndicatorSize;
+    private final int mRunningAppIndicatorTopMargin;
+    private final Paint mRunningAppIndicatorPaint;
+    private final Rect mRunningAppIconBounds = new Rect();
+    private boolean mIsRunning;
+
     @ViewDebug.ExportedProperty(category = "launcher")
     private boolean mStayPressed;
     @ViewDebug.ExportedProperty(category = "launcher")
@@ -248,6 +256,16 @@
                 defaultIconSize);
         a.recycle();
 
+        mRunningAppIndicatorSize = new Size(
+                getResources().getDimensionPixelSize(R.dimen.taskbar_running_app_indicator_width),
+                getResources().getDimensionPixelSize(R.dimen.taskbar_running_app_indicator_height));
+        mRunningAppIndicatorTopMargin =
+                getResources().getDimensionPixelSize(
+                        R.dimen.taskbar_running_app_indicator_top_margin);
+        mRunningAppIndicatorPaint = new Paint();
+        mRunningAppIndicatorPaint.setColor(getResources().getColor(
+                R.color.taskbar_running_app_indicator_color, context.getTheme()));
+
         mLongPressHelper = new CheckLongPressHelper(this);
 
         mDotParams = new DotRenderer.DrawParams();
@@ -394,6 +412,12 @@
         setDownloadStateContentDescription(info, info.getProgressLevel());
     }
 
+    /** Updates whether the app this view represents is currently running. */
+    @UiThread
+    public void updateRunningState(boolean isRunning) {
+        mIsRunning = isRunning;
+    }
+
     protected void setItemInfo(ItemInfoWithIcon itemInfo) {
         setTag(itemInfo);
     }
@@ -620,6 +644,7 @@
     public void onDraw(Canvas canvas) {
         super.onDraw(canvas);
         drawDotIfNecessary(canvas);
+        drawRunningAppIndicatorIfNecessary(canvas);
     }
 
     /**
@@ -640,6 +665,22 @@
         }
     }
 
+    /** Draws a line under the app icon if this is representing a running app in Desktop Mode. */
+    protected void drawRunningAppIndicatorIfNecessary(Canvas canvas) {
+        if (!mIsRunning || mDisplay != DISPLAY_TASKBAR) {
+            return;
+        }
+        getIconBounds(mRunningAppIconBounds);
+        // TODO(b/333872717): update color, shape, and size of indicator
+        int indicatorTop = mRunningAppIconBounds.bottom + mRunningAppIndicatorTopMargin;
+        canvas.drawRect(
+                mRunningAppIconBounds.centerX() - mRunningAppIndicatorSize.getWidth() / 2,
+                indicatorTop,
+                mRunningAppIconBounds.centerX() + mRunningAppIndicatorSize.getWidth() / 2,
+                indicatorTop + mRunningAppIndicatorSize.getHeight(),
+                mRunningAppIndicatorPaint);
+    }
+
     @Override
     public void setForceHideDot(boolean forceHideDot) {
         if (mForceHideDot == forceHideDot) {
@@ -1230,4 +1271,13 @@
     public boolean canShowLongPressPopup() {
         return getTag() instanceof ItemInfo && ShortcutUtil.supportsShortcuts((ItemInfo) getTag());
     }
+
+    /** Returns the package name of the app this icon represents. */
+    public String getTargetPackageName() {
+        Object tag = getTag();
+        if (tag instanceof ItemInfo itemInfo) {
+            return itemInfo.getTargetPackage();
+        }
+        return null;
+    }
 }
diff --git a/src/com/android/launcher3/views/DoubleShadowBubbleTextView.java b/src/com/android/launcher3/views/DoubleShadowBubbleTextView.java
index a309e6e..bc66a33 100644
--- a/src/com/android/launcher3/views/DoubleShadowBubbleTextView.java
+++ b/src/com/android/launcher3/views/DoubleShadowBubbleTextView.java
@@ -77,6 +77,7 @@
         canvas.restore();
 
         drawDotIfNecessary(canvas);
+        drawRunningAppIndicatorIfNecessary(canvas);
     }
 
     public static class ShadowInfo {