diff --git a/app/assets/javascripts/admin/addon/controllers/admin-customize-themes-show.js b/app/assets/javascripts/admin/addon/controllers/admin-customize-themes-show.js
index 453e8180e8b..a6c6f838419 100644
--- a/app/assets/javascripts/admin/addon/controllers/admin-customize-themes-show.js
+++ b/app/assets/javascripts/admin/addon/controllers/admin-customize-themes-show.js
@@ -302,7 +302,11 @@ export default class AdminCustomizeThemesShowController extends Controller {
   }
 
   get locale() {
-    return this.get("model.locale") || this.siteSettings.default_locale;
+    return (
+      this.get("model.locale") ||
+      this.userLocale ||
+      this.siteSettings.default_locale
+    );
   }
 
   @action
diff --git a/app/assets/javascripts/admin/addon/routes/admin-customize-themes-show.js b/app/assets/javascripts/admin/addon/routes/admin-customize-themes-show.js
index 55e65959173..f1377754b3a 100644
--- a/app/assets/javascripts/admin/addon/routes/admin-customize-themes-show.js
+++ b/app/assets/javascripts/admin/addon/routes/admin-customize-themes-show.js
@@ -41,6 +41,7 @@ export default class AdminCustomizeThemesShowRoute extends Route {
       colorSchemes: parentController.get("model.extras.color_schemes"),
       editingName: false,
       editingThemeSetting: false,
+      userLocale: parentController.get("model.extras.locale"),
     });
 
     this.handleHighlight(model);
diff --git a/app/controllers/admin/themes_controller.rb b/app/controllers/admin/themes_controller.rb
index 3767e39db85..16c1c50729b 100644
--- a/app/controllers/admin/themes_controller.rb
+++ b/app/controllers/admin/themes_controller.rb
@@ -176,6 +176,7 @@ class Admin::ThemesController < Admin::AdminController
       themes: serialize_data(@themes, ThemeSerializer),
       extras: {
         color_schemes: serialize_data(@color_schemes, ColorSchemeSerializer),
+        locale: current_user.effective_locale,
       },
     }
 
diff --git a/spec/system/admin_customize_themes_spec.rb b/spec/system/admin_customize_themes_spec.rb
index be62b4b6da9..0403aef2510 100644
--- a/spec/system/admin_customize_themes_spec.rb
+++ b/spec/system/admin_customize_themes_spec.rb
@@ -3,7 +3,7 @@
 describe "Admin Customize Themes", type: :system do
   fab!(:color_scheme)
   fab!(:theme)
-  fab!(:admin)
+  fab!(:admin) { Fabricate(:admin, locale: "en") }
 
   let(:admin_customize_themes_page) { PageObjects::Pages::AdminCustomizeThemes.new }
 
@@ -160,5 +160,33 @@ describe "Admin Customize Themes", type: :system do
       theme_translations_settings_editor.fill_in("Hello World in French")
       theme_translations_settings_editor.save
     end
+
+    it "should match the current user locale translation" do
+      SiteSetting.allow_user_locale = true
+      SiteSetting.set_locale_from_accept_language_header = true
+      SiteSetting.default_locale = "fr"
+
+      theme.set_field(
+        target: :translations,
+        name: "en",
+        value: { en: { group: { hello: "Hello there!" } } }.deep_stringify_keys.to_yaml,
+      )
+      theme.set_field(
+        target: :translations,
+        name: "fr",
+        value: { fr: { group: { hello: "Bonjour!" } } }.deep_stringify_keys.to_yaml,
+      )
+      theme.save!
+
+      visit("/admin/customize/themes/#{theme.id}")
+
+      theme_translations_settings_editor =
+        PageObjects::Components::AdminThemeTranslationsSettingsEditor.new
+
+      expect(theme_translations_settings_editor.get_input_value).to have_content("Hello there!")
+
+      theme_translations_picker = PageObjects::Components::SelectKit.new(".translation-selector")
+      expect(theme_translations_picker.component.text).to eq("English (US)")
+    end
   end
 end