diff --git a/ui/gtk/native_theme_gtk.cc b/ui/gtk/native_theme_gtk.cc
index 4afa399..fbaaf06e 100644
--- a/ui/gtk/native_theme_gtk.cc
+++ b/ui/gtk/native_theme_gtk.cc
@@ -116,6 +116,13 @@
   ui::ColorProviderManager::Get().AppendColorProviderInitializer(
       base::BindRepeating(AddGtkNativeCoreColorMixer));
 
+  // Add the web native theme as an observer to stay in sync with dark mode,
+  // high contrast, and preferred color scheme changes.
+  color_scheme_observer_ =
+      std::make_unique<NativeTheme::ColorSchemeNativeThemeObserver>(
+          NativeTheme::GetInstanceForWeb());
+  AddObserver(color_scheme_observer_.get());
+
   OnThemeChanged(gtk_settings_get_default(), nullptr);
 }
 
diff --git a/ui/gtk/native_theme_gtk.h b/ui/gtk/native_theme_gtk.h
index 876a738..ad3b88d41 100644
--- a/ui/gtk/native_theme_gtk.h
+++ b/ui/gtk/native_theme_gtk.h
@@ -93,6 +93,11 @@
   mutable absl::optional<SkColor> color_cache_[kColorId_NumColors];
 
   ScopedCssProvider theme_css_override_;
+
+  // Used to notify the web native theme of changes to dark mode, high
+  // contrast, and preferred color scheme.
+  std::unique_ptr<NativeTheme::ColorSchemeNativeThemeObserver>
+      color_scheme_observer_;
 };
 
 }  // namespace gtk