diff --git a/android/java/org/chromium/chrome/browser/BraveActivity.java b/android/java/org/chromium/chrome/browser/BraveActivity.java
index 5693b4af44b1..6bff24883c1b 100644
--- a/android/java/org/chromium/chrome/browser/BraveActivity.java
+++ b/android/java/org/chromium/chrome/browser/BraveActivity.java
@@ -12,6 +12,7 @@
 import android.content.Intent;
 import android.content.pm.PackageManager;
 import android.content.pm.ResolveInfo;
+import android.content.SharedPreferences;
 import android.net.Uri;
 import android.os.Build;
 import android.provider.Settings;
@@ -37,6 +38,7 @@
 import org.chromium.chrome.browser.onboarding.OnboardingPrefManager;
 import org.chromium.chrome.browser.preferences.Pref;
 import org.chromium.chrome.browser.preferences.PrefServiceBridge;
+import org.chromium.chrome.browser.settings.BraveRewardsPreferences;
 import org.chromium.chrome.browser.settings.BraveSearchEngineUtils;
 import org.chromium.chrome.browser.share.ShareDelegate;
 import org.chromium.chrome.browser.tab.Tab;
@@ -187,6 +189,9 @@ public void finishNativeInitialization() {
         int appOpenCount = ContextUtils.getAppSharedPreferences().getInt(BackgroundImagesPreferences.PREF_APP_OPEN_COUNT, 0);
         BackgroundImagesPreferences.setOnPreferenceValue(BackgroundImagesPreferences.PREF_APP_OPEN_COUNT , appOpenCount + 1);
 
+        //set bg ads to off for existing and new installations
+        setBgBraveAdsDefaultOff();
+
         Context app = ContextUtils.getApplicationContext();
         if (null != app && (this instanceof ChromeTabbedActivity)) {
             mBraveSyncWorker = new BraveSyncWorker(app);
@@ -413,4 +418,23 @@ public void onActivityResult (int requestCode, int resultCode,
         }
         super.onActivityResult(requestCode, resultCode, data);
     }
+
+    /**
+     * Disable background ads on Android. Issue #8641.
+     */
+    private void setBgBraveAdsDefaultOff() {
+        SharedPreferences sharedPreferences =
+                ContextUtils.getAppSharedPreferences();
+        boolean exists = sharedPreferences.contains(
+                BraveRewardsPreferences.PREF_ADS_SWITCH_DEFAULT_HAS_BEEN_SET);
+        if (!exists) {
+            SharedPreferences.Editor sharedPreferencesEditor =
+                    sharedPreferences.edit();
+            sharedPreferencesEditor.putBoolean(
+                    BraveRewardsPreferences.PREF_ADS_SWITCH, false);
+            sharedPreferencesEditor.putBoolean(
+                    BraveRewardsPreferences.PREF_ADS_SWITCH_DEFAULT_HAS_BEEN_SET, true);
+            sharedPreferencesEditor.apply();
+        }
+    }
 }
diff --git a/android/java/org/chromium/chrome/browser/settings/BraveRewardsPreferences.java b/android/java/org/chromium/chrome/browser/settings/BraveRewardsPreferences.java
index 5de884664d25..087a9b7e8ddf 100644
--- a/android/java/org/chromium/chrome/browser/settings/BraveRewardsPreferences.java
+++ b/android/java/org/chromium/chrome/browser/settings/BraveRewardsPreferences.java
@@ -23,7 +23,10 @@
  */
 public class BraveRewardsPreferences extends BravePreferenceFragment
         implements OnPreferenceChangeListener, BraveRewardsObserver {
-    private static final String PREF_ADS_SWITCH = "ads_switch";
+    public static final String PREF_ADS_SWITCH = "ads_switch";
+
+    // flag, if exists: default state (off) for background Brave ads has been set
+    public static final String PREF_ADS_SWITCH_DEFAULT_HAS_BEEN_SET = "ads_switch_default_set";
 
     private ChromeSwitchPreference mAdsSwitch;