diff -urN gtk-3.24.52-orig/gdk/wayland/gdkdisplay-wayland.c gtk-3.24.52/gdk/wayland/gdkdisplay-wayland.c
--- gtk-3.24.52-orig/gdk/wayland/gdkdisplay-wayland.c	2026-03-23 11:24:49 +0900
+++ gtk-3.24.52/gdk/wayland/gdkdisplay-wayland.c	2026-09-03 00:32:26 +0900
@@ -559,6 +559,12 @@
         wl_registry_bind (display_wayland->wl_registry, id,
                           &wp_cursor_shape_manager_v1_interface, 1);
     }
+  else if (strcmp (interface, xdg_toplevel_icon_manager_v1_interface.name) == 0)
+    {
+      display_wayland->xdg_toplevel_icon_manager =
+        wl_registry_bind (display_wayland->wl_registry, id,
+                          &xdg_toplevel_icon_manager_v1_interface, 1);
+    }
 
   g_hash_table_insert (display_wayland->known_globals,
                        GUINT_TO_POINTER (id), g_strdup (interface));
diff -urN gtk-3.24.52-orig/gdk/wayland/gdkdisplay-wayland.h gtk-3.24.52/gdk/wayland/gdkdisplay-wayland.h
--- gtk-3.24.52-orig/gdk/wayland/gdkdisplay-wayland.h	2026-03-23 11:24:49 +0900
+++ gtk-3.24.52/gdk/wayland/gdkdisplay-wayland.h	2026-09-02 21:49:03 +0900
@@ -41,6 +41,7 @@
 #include <gdk/wayland/xdg-activation-v1-client-protocol.h>
 #endif
 #include <gdk/wayland/cursor-shape-v1-client-protocol.h>
+#include <gdk/wayland/xdg-toplevel-icon-v1-client-protocol.h>
 
 #include <glib.h>
 #include <gdk/gdkkeys.h>
@@ -110,6 +111,7 @@
   struct xdg_activation_v1 *xdg_activation;
 #endif
   struct wp_cursor_shape_manager_v1 *cursor_shape;
+  struct xdg_toplevel_icon_manager_v1 *xdg_toplevel_icon_manager;
 
   GList *async_roundtrips;
 
diff -urN gtk-3.24.52-orig/gdk/wayland/gdkwindow-wayland.c gtk-3.24.52/gdk/wayland/gdkwindow-wayland.c
--- gtk-3.24.52-orig/gdk/wayland/gdkwindow-wayland.c	2026-03-23 11:24:49 +0900
+++ gtk-3.24.52/gdk/wayland/gdkwindow-wayland.c	2026-09-03 03:05:16 +0900
@@ -124,6 +124,8 @@
     struct xdg_toplevel *xdg_toplevel;
     struct xdg_popup *xdg_popup;
 
+    struct xdg_toplevel_icon_v1 *xdg_toplevel_icon;
+
     /* Legacy xdg-shell unstable v6 fallback support */
     struct zxdg_surface_v6 *zxdg_surface_v6;
     struct zxdg_toplevel_v6 *zxdg_toplevel_v6;
@@ -2038,6 +2040,11 @@
   xdg_toplevel_add_listener (impl->display_server.xdg_toplevel,
                              &xdg_toplevel_listener,
                              window);
+
+  if (impl->display_server.xdg_toplevel_icon)
+    xdg_toplevel_icon_manager_v1_set_icon (display_wayland->xdg_toplevel_icon_manager,
+                                           impl->display_server.xdg_toplevel,
+                                           impl->display_server.xdg_toplevel_icon);
 }
 
 static void
@@ -4419,6 +4426,81 @@
 gdk_wayland_window_set_icon_list (GdkWindow *window,
                                   GList     *pixbufs)
 {
+  GdkWindowImplWayland *impl;
+  GdkWaylandDisplay *display_wayland;
+  struct xdg_toplevel_icon_manager_v1 *manager;
+  struct xdg_toplevel_icon_v1 *icon;
+  GList *l;
+
+  if (GDK_WINDOW_DESTROYED (window) ||
+      !WINDOW_IS_TOPLEVEL_OR_FOREIGN (window))
+    return;
+
+  impl = GDK_WINDOW_IMPL_WAYLAND (window->impl);
+  display_wayland = GDK_WAYLAND_DISPLAY (gdk_window_get_display (window));
+
+  manager = display_wayland->xdg_toplevel_icon_manager;
+  if (!manager)
+    return;
+
+  // FIXME(achurch): this is a trivial implementation that leaks all objects
+
+  icon = xdg_toplevel_icon_manager_v1_create_icon (manager);
+
+  l = pixbufs;
+  while (l)
+    {
+      GdkPixbuf *pixbuf;
+      cairo_surface_t *surface;
+      struct wl_buffer *buffer;
+      gint width, height, stride_in, stride_out, n_channels;
+      guchar *pixels_in;
+      guint32 *pixels_out;
+      gint x, y;
+
+      pixbuf = l->data;
+      width = gdk_pixbuf_get_width (pixbuf);
+      height = gdk_pixbuf_get_height (pixbuf);
+      stride_in = gdk_pixbuf_get_rowstride (pixbuf);
+      n_channels = gdk_pixbuf_get_n_channels (pixbuf);
+      pixels_in = gdk_pixbuf_get_pixels (pixbuf);
+
+      surface = _gdk_wayland_display_create_shm_surface (display_wayland,
+                                                         width,
+                                                         height,
+                                                         1);
+      stride_out = cairo_image_surface_get_stride (surface) / 4;
+      pixels_out = (guint32 *) cairo_image_surface_get_data (surface);
+
+      for (y = 0; y < height; y++)
+	{
+	  for (x = 0; x < width; x++)
+	    {
+	      guchar r, g, b, a;
+	      
+	      r = pixels_in[y*stride_in + x*n_channels + 0];
+	      g = pixels_in[y*stride_in + x*n_channels + 1];
+	      b = pixels_in[y*stride_in + x*n_channels + 2];
+	      if (n_channels >= 4)
+		a = pixels_in[y*stride_in + x*n_channels + 3];
+	      else
+		a = 255;
+
+	      pixels_out[y*stride_out + x] = a << 24 | r << 16 | g << 8 | b;
+	    }
+	}
+
+      buffer = _gdk_wayland_shm_surface_get_wl_buffer (surface);
+      xdg_toplevel_icon_v1_add_buffer (icon, buffer, 1);
+
+      l = l->next;
+    }
+
+  impl->display_server.xdg_toplevel_icon = icon;
+  if (impl->display_server.xdg_toplevel)
+    xdg_toplevel_icon_manager_v1_set_icon (manager,
+                                           impl->display_server.xdg_toplevel,
+                                           icon);
 }
 
 static void
diff -urN gtk-3.24.52-orig/gdk/wayland/meson.build gtk-3.24.52/gdk/wayland/meson.build
--- gtk-3.24.52-orig/gdk/wayland/meson.build	2026-03-23 11:24:49 +0900
+++ gtk-3.24.52/gdk/wayland/meson.build	2026-09-02 21:46:23 +0900
@@ -60,6 +60,7 @@
   ['xdg-output', 'unstable', 'v1', ],
   ['primary-selection', 'unstable', 'v1', ],
   ['cursor-shape-v1', 'private', ],
+  ['xdg-toplevel-icon', 'staging', 'v1', ],
 ]
 if wlprotocolsdep.version().version_compare('>=1.21')
   proto_sources += [['xdg-activation', 'staging', 'v1', ]]