diff --git a/res/xml/accessibility_button_settings.xml b/res/xml/accessibility_button_settings.xml
index e348b77ffb0..8d4631afbba 100644
--- a/res/xml/accessibility_button_settings.xml
+++ b/res/xml/accessibility_button_settings.xml
@@ -47,7 +47,8 @@
         android:key="accessibility_button_opacity"
         android:title="@string/accessibility_button_opacity_title"
         android:selectable="true"
-        android:persistent="false"/>
+        android:persistent="false"
+        settings:controller="com.android.settings.accessibility.FloatingMenuOpacityPreferenceController"/>
 
     <com.android.settingslib.widget.FooterPreference
         android:key="accessibility_button_footer"
diff --git a/src/com/android/settings/accessibility/FloatingMenuOpacityPreferenceController.java b/src/com/android/settings/accessibility/FloatingMenuOpacityPreferenceController.java
new file mode 100644
index 00000000000..d31e9a9bdc6
--- /dev/null
+++ b/src/com/android/settings/accessibility/FloatingMenuOpacityPreferenceController.java
@@ -0,0 +1,142 @@
+/*
+ * Copyright (C) 2021 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.settings.accessibility;
+
+import android.content.ContentResolver;
+import android.content.Context;
+import android.database.ContentObserver;
+import android.os.Handler;
+import android.os.Looper;
+import android.provider.Settings;
+
+import androidx.annotation.VisibleForTesting;
+import androidx.preference.PreferenceScreen;
+
+import com.android.settings.core.SliderPreferenceController;
+import com.android.settings.widget.SeekBarPreference;
+import com.android.settingslib.core.lifecycle.LifecycleObserver;
+import com.android.settingslib.core.lifecycle.events.OnPause;
+import com.android.settingslib.core.lifecycle.events.OnResume;
+
+/** Preference controller that controls the opacity seekbar in accessibility button page. */
+public class FloatingMenuOpacityPreferenceController extends SliderPreferenceController
+        implements LifecycleObserver, OnResume, OnPause {
+
+    @VisibleForTesting
+    static final float DEFAULT_OPACITY = 0.55f;
+    private static final float MIN_PROGRESS = 10f;
+    private static final float MAX_PROGRESS = 100f;
+    @VisibleForTesting
+    static final float PRECISION = 100f;
+
+    private final ContentResolver mContentResolver;
+    @VisibleForTesting
+    final ContentObserver mContentObserver;
+
+    @VisibleForTesting
+    SeekBarPreference mPreference;
+
+    public FloatingMenuOpacityPreferenceController(Context context,
+            String preferenceKey) {
+        super(context, preferenceKey);
+        mContentResolver = context.getContentResolver();
+        mContentObserver = new ContentObserver(new Handler(Looper.getMainLooper())) {
+            @Override
+            public void onChange(boolean selfChange) {
+                updateAvailabilityStatus();
+            }
+        };
+    }
+
+    @Override
+    public int getAvailabilityStatus() {
+        return AccessibilityUtil.isFloatingMenuEnabled(mContext)
+                ? AVAILABLE : DISABLED_DEPENDENT_SETTING;
+    }
+
+    @Override
+    public void displayPreference(PreferenceScreen screen) {
+        super.displayPreference(screen);
+
+        mPreference = screen.findPreference(getPreferenceKey());
+        mPreference.setContinuousUpdates(true);
+        mPreference.setMax(getMax());
+        mPreference.setMin(getMin());
+        mPreference.setHapticFeedbackMode(SeekBarPreference.HAPTIC_FEEDBACK_MODE_ON_ENDS);
+
+        updateState(mPreference);
+    }
+
+    @Override
+    public void onResume() {
+        mContentResolver.registerContentObserver(
+                Settings.Secure.getUriFor(
+                        Settings.Secure.ACCESSIBILITY_BUTTON_MODE), /* notifyForDescendants= */
+                false, mContentObserver);
+
+    }
+
+    @Override
+    public void onPause() {
+        mContentResolver.unregisterContentObserver(mContentObserver);
+    }
+
+    @Override
+    public int getSliderPosition() {
+        return convertOpacityFloatToInt(getOpacity());
+    }
+
+    @Override
+    public boolean setSliderPosition(int position) {
+        final float value = convertOpacityIntToFloat(position);
+
+        return Settings.Secure.putFloat(mContentResolver,
+                Settings.Secure.ACCESSIBILITY_FLOATING_MENU_OPACITY, value);
+    }
+
+    @Override
+    public int getMax() {
+        return (int) MAX_PROGRESS;
+    }
+
+    @Override
+    public int getMin() {
+        return (int) MIN_PROGRESS;
+    }
+
+    private void updateAvailabilityStatus() {
+        mPreference.setEnabled(AccessibilityUtil.isFloatingMenuEnabled(mContext));
+    }
+
+    private int convertOpacityFloatToInt(float value) {
+        return Math.round(value * PRECISION);
+    }
+
+    private float convertOpacityIntToFloat(int value) {
+        return (float) value / PRECISION;
+    }
+
+    private float getOpacity() {
+        float value = Settings.Secure.getFloat(mContentResolver,
+                Settings.Secure.ACCESSIBILITY_FLOATING_MENU_OPACITY, DEFAULT_OPACITY);
+        final float minValue = MIN_PROGRESS / PRECISION;
+        final float maxValue = MAX_PROGRESS / PRECISION;
+
+        return (value < minValue || value > maxValue) ? DEFAULT_OPACITY : value;
+    }
+}
+
diff --git a/tests/robotests/src/com/android/settings/accessibility/FloatingMenuOpacityPreferenceControllerTest.java b/tests/robotests/src/com/android/settings/accessibility/FloatingMenuOpacityPreferenceControllerTest.java
new file mode 100644
index 00000000000..98ad00a8fda
--- /dev/null
+++ b/tests/robotests/src/com/android/settings/accessibility/FloatingMenuOpacityPreferenceControllerTest.java
@@ -0,0 +1,137 @@
+/*
+ * Copyright (C) 2021 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.settings.accessibility;
+
+import static android.provider.Settings.Secure.ACCESSIBILITY_BUTTON_MODE_FLOATING_MENU;
+import static android.provider.Settings.Secure.ACCESSIBILITY_BUTTON_MODE_NAVIGATION_BAR;
+
+import static com.android.settings.accessibility.FloatingMenuOpacityPreferenceController.DEFAULT_OPACITY;
+import static com.android.settings.accessibility.FloatingMenuOpacityPreferenceController.PRECISION;
+import static com.android.settings.core.BasePreferenceController.AVAILABLE;
+import static com.android.settings.core.BasePreferenceController.DISABLED_DEPENDENT_SETTING;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+import android.content.ContentResolver;
+import android.content.Context;
+import android.provider.Settings;
+
+import androidx.test.core.app.ApplicationProvider;
+
+import com.android.settings.widget.SeekBarPreference;
+
+import org.junit.Before;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.Mock;
+import org.mockito.Spy;
+import org.mockito.junit.MockitoJUnit;
+import org.mockito.junit.MockitoRule;
+import org.robolectric.RobolectricTestRunner;
+
+/** Tests for {@link FloatingMenuOpacityPreferenceController}. */
+@RunWith(RobolectricTestRunner.class)
+public class FloatingMenuOpacityPreferenceControllerTest {
+
+    @Rule
+    public MockitoRule mocks = MockitoJUnit.rule();
+
+    @Spy
+    private final Context mContext = ApplicationProvider.getApplicationContext();
+    @Mock
+    private ContentResolver mContentResolver;
+    private FloatingMenuOpacityPreferenceController mController;
+
+    @Before
+    public void setUp() {
+        when(mContext.getContentResolver()).thenReturn(mContentResolver);
+        mController = new FloatingMenuOpacityPreferenceController(mContext, "test_key");
+    }
+
+    @Test
+    public void getAvailabilityStatus_a11yBtnModeFloatingMenu_returnAvailable() {
+        Settings.Secure.putInt(mContentResolver, Settings.Secure.ACCESSIBILITY_BUTTON_MODE,
+                ACCESSIBILITY_BUTTON_MODE_FLOATING_MENU);
+
+        assertThat(mController.getAvailabilityStatus()).isEqualTo(AVAILABLE);
+    }
+
+    @Test
+    public void getAvailabilityStatus_a11yBtnModeNavigationBar_returnDisabledDependentSetting() {
+        Settings.Secure.putInt(mContentResolver, Settings.Secure.ACCESSIBILITY_BUTTON_MODE,
+                ACCESSIBILITY_BUTTON_MODE_NAVIGATION_BAR);
+
+        assertThat(mController.getAvailabilityStatus()).isEqualTo(DISABLED_DEPENDENT_SETTING);
+    }
+
+    @Test
+    public void onChange_a11yBtnModeChangeToNavigationBar_preferenceDisabled() {
+        mController.mPreference = new SeekBarPreference(mContext);
+        Settings.Secure.putInt(mContentResolver, Settings.Secure.ACCESSIBILITY_BUTTON_MODE,
+                ACCESSIBILITY_BUTTON_MODE_NAVIGATION_BAR);
+
+        mController.mContentObserver.onChange(false);
+
+        assertThat(mController.mPreference.isEnabled()).isFalse();
+    }
+
+    @Test
+    public void getSliderPosition_putNormalOpacityValue_expectedValue() {
+        Settings.Secure.putFloat(mContext.getContentResolver(),
+                Settings.Secure.ACCESSIBILITY_FLOATING_MENU_OPACITY, 0.35f);
+
+        assertThat(mController.getSliderPosition()).isEqualTo(35);
+    }
+
+    @Test
+    public void getSliderPosition_putOutOfBoundOpacityValue_defaultValue() {
+        Settings.Secure.putFloat(mContext.getContentResolver(),
+                Settings.Secure.ACCESSIBILITY_FLOATING_MENU_OPACITY, 0.01f);
+
+        final int defaultValue = Math.round(DEFAULT_OPACITY * PRECISION);
+        assertThat(mController.getSliderPosition()).isEqualTo(defaultValue);
+    }
+
+    @Test
+    public void setSliderPosition_expectedValue() {
+        mController.setSliderPosition(27);
+
+        final float value = Settings.Secure.getFloat(mContext.getContentResolver(),
+                Settings.Secure.ACCESSIBILITY_FLOATING_MENU_OPACITY, -1);
+        assertThat(value).isEqualTo(0.27f);
+    }
+
+    @Test
+    public void onResume_registerSpecificContentObserver() {
+        mController.onResume();
+
+        verify(mContentResolver).registerContentObserver(
+                Settings.Secure.getUriFor(Settings.Secure.ACCESSIBILITY_BUTTON_MODE), false,
+                mController.mContentObserver);
+    }
+
+    @Test
+    public void onPause_unregisterContentObserver() {
+        mController.onPause();
+
+        verify(mContentResolver).unregisterContentObserver(mController.mContentObserver);
+    }
+}