diff --git a/src/com/android/customization/model/theme/custom/CustomThemeManager.java b/src/com/android/customization/model/theme/custom/CustomThemeManager.java
index 7b9b67c..f4466e0 100644
--- a/src/com/android/customization/model/theme/custom/CustomThemeManager.java
+++ b/src/com/android/customization/model/theme/custom/CustomThemeManager.java
@@ -16,20 +16,29 @@
 package com.android.customization.model.theme.custom;
 
 import android.content.Context;
+import android.os.Bundle;
+import android.text.TextUtils;
+import android.util.Log;
 
 import androidx.annotation.Nullable;
 
 import com.android.customization.model.CustomizationManager;
 import com.android.customization.model.theme.ThemeBundle.PreviewInfo;
+import com.android.customization.model.theme.ThemeBundleProvider;
 import com.android.customization.model.theme.ThemeManager;
 import com.android.customization.model.theme.custom.CustomTheme.Builder;
 
+import org.json.JSONException;
+
 import java.util.Map;
 
 public class CustomThemeManager implements CustomizationManager<ThemeComponentOption> {
 
+    private static final String TAG = "CustomThemeManager";
+    private static final String EXTRA_CUSTOM_THEME_OPTION = "custom_theme_option";
+
     private final CustomTheme mOriginalTheme;
-    private final CustomTheme.Builder mBuilder;
+    private CustomTheme.Builder mBuilder;
 
     private CustomThemeManager(Map<String, String> overlayPackages,
             @Nullable CustomTheme originalTheme) {
@@ -72,6 +81,29 @@
         return mBuilder.createPreviewInfo(context);
     }
 
+    /** Saves the custom theme selections while system config changes. */
+    public void saveCustomTheme(Context context, Bundle savedInstanceState) {
+        CustomTheme customTheme =
+                buildPartialCustomTheme(context, /* id= */ null, /* title= */ null);
+        savedInstanceState.putString(EXTRA_CUSTOM_THEME_OPTION,
+                customTheme.getSerializedPackages());
+    }
+
+    /** Reads the saved custom theme after system config changed. */
+    public void readCustomTheme(ThemeBundleProvider themeBundleProvider,
+                                Bundle savedInstanceState) {
+        String packages = savedInstanceState.getString(EXTRA_CUSTOM_THEME_OPTION);
+        if (!TextUtils.isEmpty(packages)) {
+            try {
+                mBuilder = themeBundleProvider.parseCustomTheme(packages);
+            } catch (JSONException e) {
+                Log.w(TAG, "Couldn't parse provided custom theme.");
+            }
+        } else {
+            Log.w(TAG, "No custom theme being restored.");
+        }
+    }
+
     public static CustomThemeManager create(
             @Nullable CustomTheme customTheme, ThemeManager themeManager) {
         if (customTheme != null && customTheme.isDefined()) {
diff --git a/src/com/android/customization/picker/theme/CustomThemeActivity.java b/src/com/android/customization/picker/theme/CustomThemeActivity.java
index a5ce222..1cfdf93 100644
--- a/src/com/android/customization/picker/theme/CustomThemeActivity.java
+++ b/src/com/android/customization/picker/theme/CustomThemeActivity.java
@@ -85,12 +85,12 @@
     protected void onCreate(Bundle savedInstanceState) {
         CustomizationInjector injector = (CustomizationInjector) InjectorProvider.getInjector();
         mUserEventLogger = (ThemesUserEventLogger) injector.getUserEventLogger(this);
+        ThemeBundleProvider themeProvider =
+                new DefaultThemeProvider(this, injector.getCustomizationPreferences(this));
         Intent intent = getIntent();
         CustomTheme customTheme = null;
         if (intent != null && intent.hasExtra(EXTRA_THEME_PACKAGES)
                 && intent.hasExtra(EXTRA_THEME_TITLE) && intent.hasExtra(EXTRA_THEME_ID)) {
-            ThemeBundleProvider themeProvider =
-                    new DefaultThemeProvider(this, injector.getCustomizationPreferences(this));
             mIsDefinedTheme = intent.getBooleanExtra(CREATE_NEW_THEME, true);
             try {
                 CustomTheme.Builder themeBuilder = themeProvider.parseCustomTheme(
@@ -112,6 +112,9 @@
                 mUserEventLogger);
         mThemeManager.fetchOptions(null, false);
         mCustomThemeManager = CustomThemeManager.create(customTheme, mThemeManager);
+        if (savedInstanceState != null) {
+            mCustomThemeManager.readCustomTheme(themeProvider, savedInstanceState);
+        }
 
         int currentStep = 0;
         if (savedInstanceState != null) {
@@ -138,6 +141,9 @@
     protected void onSaveInstanceState(Bundle outState) {
         super.onSaveInstanceState(outState);
         outState.putInt(KEY_STATE_CURRENT_STEP, mCurrentStep);
+        if (mCustomThemeManager != null) {
+            mCustomThemeManager.saveCustomTheme(this, outState);
+        }
     }
 
     private void navigateToStep(int i) {