diff --git a/loko/assets/static/assets/unified_index.js b/loko/assets/static/assets/unified_index.js
index c2b8ade..2218f18 100644
--- a/loko/assets/static/assets/unified_index.js
+++ b/loko/assets/static/assets/unified_index.js
@@ -748,6 +748,14 @@ function applyInitialPreferences() {
             window._restoredMapCenter = prefs.map_center;
             window._restoredMapZoom = prefs.map_zoom;
         }
+
+        // Basemap preference
+        if (prefs.basemap) {
+            window._restoredBasemap = prefs.basemap;
+            try {
+                localStorage.setItem('loko_active_basemap', prefs.basemap);
+            } catch (e) {}
+        }
     } else if (DEFAULT_THEMATIC_CODE && DEFAULT_THEMATIC_CODE in THEMATIC_CONFIG) {
         // First visit: pre-select the user's default thematic
         activeThematics = new Set([DEFAULT_THEMATIC_CODE]);
@@ -775,6 +783,9 @@ function savePreferences() {
     ).map(cb => cb.value);
     const includeNoGeomCheckbox = document.getElementById('include-no-geom');
     const includeNoGeom = includeNoGeomCheckbox ? includeNoGeomCheckbox.checked : true;
+    const activeBasemap = (window.unifiedLayerSwitcher && window.unifiedLayerSwitcher.activeBasemapId)
+        || localStorage.getItem('loko_active_basemap')
+        || 'default';
     const prefs = {
         thematics: Array.from(activeThematics),
         categories: Array.from(activeCategories),
@@ -787,6 +798,7 @@ function savePreferences() {
         include_no_geom: includeNoGeom,
         map_center: (typeof map !== 'undefined' && map.getCenter) ? [map.getCenter().lng, map.getCenter().lat] : null,
         map_zoom: (typeof map !== 'undefined' && map.getZoom) ? map.getZoom() : null,
+        basemap: activeBasemap,
     };
     fetch(SAVE_ASSETS_PREFS_URL, {
         method: 'POST',
@@ -2929,7 +2941,12 @@ maploader.addEventListener('mapLoaded', () => {
 
     // Layer switcher — Urbis & Vlaanderen orthos (top-right, topmost)
     if (typeof LayerSwitcherControl !== 'undefined') {
+        const initialBasemap = window._restoredBasemap || localStorage.getItem('loko_active_basemap') || 'default';
         const layerSwitcher = new LayerSwitcherControl({
+            initialBasemapId: initialBasemap,
+            onBasemapChange: function (basemapId) {
+                schedulePreferencesSave();
+            },
             layers: [{
                 id: 'basemap',
                 name: 'Fonds de plan & Orthophotos',
@@ -2937,7 +2954,10 @@ maploader.addEventListener('mapLoaded', () => {
                 beforeLayer: (map && map.getLayer('territory-mask') ? 'territory-mask' : 'locations'),
                 basemaps: window.MAP_BACKGROUNDS || [],
             }],
-        });// Reset view — fly back to initial Brussels Region view
+        });
+        window.unifiedLayerSwitcher = layerSwitcher;
+
+        // Reset view — fly back to initial Brussels Region view
         map.addControl({
             onAdd(m) {
                 this._map = m;
diff --git a/loko/assets/templates/assets/unified_index.html b/loko/assets/templates/assets/unified_index.html
index e7dea0c..ebe2085 100644
--- a/loko/assets/templates/assets/unified_index.html
+++ b/loko/assets/templates/assets/unified_index.html
@@ -1315,7 +1315,7 @@
 
 {% block script %}
     <script src="{% static 'common/mapbox-gl-draw.js' %}"></script>
-    <script src="{% static 'common/layer-switcher-control.js' %}"></script>
+    <script src="{% static 'common/layer-switcher-control.js' %}?v=20261009_basemap"></script>
     <script>
         window.TERRITORY_MASK_URL = "{% url 'common:get_territory_mask_geojson' %}";
         const preventive_draft_id = "{{ preventive_draft_id|default:'' }}";
@@ -1374,5 +1374,5 @@
     <script src="{% static 'assets/sign_panels_shared.js' %}?v=20260703c"></script>
     <script src="{% static 'assets/asset_symbology.js' %}?v=20261009_tree_icons"></script>
     <script src="{% static 'assets/unified_map_layers.js' %}?v=20261009_tree_icons"></script>
-    <script src="{% static 'assets/unified_index.js' %}?v=20261009_tree_icons"></script>
+    <script src="{% static 'assets/unified_index.js' %}?v=20261009_basemap"></script>
 {% endblock script %}
\ No newline at end of file
diff --git a/loko/common/locale/en/LC_MESSAGES/django.mo b/loko/common/locale/en/LC_MESSAGES/django.mo
index 7eb40fc..a64342f 100644
Binary files a/loko/common/locale/en/LC_MESSAGES/django.mo and b/loko/common/locale/en/LC_MESSAGES/django.mo differ
diff --git a/loko/common/locale/en/LC_MESSAGES/django.po b/loko/common/locale/en/LC_MESSAGES/django.po
index cdbbd5c..5c1f710 100644
--- a/loko/common/locale/en/LC_MESSAGES/django.po
+++ b/loko/common/locale/en/LC_MESSAGES/django.po
@@ -553,3 +553,8 @@ msgstr "Zoom in"
 #: common/templates/common/components/document_viewer.html
 msgid "Réinitialiser"
 msgstr "Reset"
+
+#: common/views.py:683
+msgid "Format de fond de plan invalide"
+msgstr "Invalid basemap format"
+
diff --git a/loko/common/locale/fr/LC_MESSAGES/django.mo b/loko/common/locale/fr/LC_MESSAGES/django.mo
index 8d040b2..94e12ae 100644
Binary files a/loko/common/locale/fr/LC_MESSAGES/django.mo and b/loko/common/locale/fr/LC_MESSAGES/django.mo differ
diff --git a/loko/common/locale/fr/LC_MESSAGES/django.po b/loko/common/locale/fr/LC_MESSAGES/django.po
index 0b12f73..b125da3 100644
--- a/loko/common/locale/fr/LC_MESSAGES/django.po
+++ b/loko/common/locale/fr/LC_MESSAGES/django.po
@@ -539,3 +539,8 @@ msgstr "Zoomer"
 #: common/templates/common/components/document_viewer.html
 msgid "Réinitialiser"
 msgstr "Réinitialiser"
+
+#: common/views.py:683
+msgid "Format de fond de plan invalide"
+msgstr "Format de fond de plan invalide"
+
diff --git a/loko/common/locale/nl/LC_MESSAGES/django.mo b/loko/common/locale/nl/LC_MESSAGES/django.mo
index e47b6d7..d8192e4 100644
Binary files a/loko/common/locale/nl/LC_MESSAGES/django.mo and b/loko/common/locale/nl/LC_MESSAGES/django.mo differ
diff --git a/loko/common/locale/nl/LC_MESSAGES/django.po b/loko/common/locale/nl/LC_MESSAGES/django.po
index dd7466b..bc848c5 100644
--- a/loko/common/locale/nl/LC_MESSAGES/django.po
+++ b/loko/common/locale/nl/LC_MESSAGES/django.po
@@ -539,3 +539,8 @@ msgstr "Inzoomen"
 #: common/templates/common/components/document_viewer.html
 msgid "Réinitialiser"
 msgstr "Herstellen"
+
+#: common/views.py:683
+msgid "Format de fond de plan invalide"
+msgstr "Ongeldig basiskaartformaat"
+
diff --git a/loko/common/static/common/layer-switcher-control.js b/loko/common/static/common/layer-switcher-control.js
index 5e37a1d..495b05f 100644
--- a/loko/common/static/common/layer-switcher-control.js
+++ b/loko/common/static/common/layer-switcher-control.js
@@ -381,7 +381,8 @@
             
             // Extract or build basemaps list
             this.basemaps = this._resolveBasemaps();
-            this.activeBasemapId = localStorage.getItem('loko_active_basemap') || 'default';
+            this.activeBasemapId = options.initialBasemapId || localStorage.getItem('loko_active_basemap') || 'default';
+            this.onBasemapChange = typeof options.onBasemapChange === 'function' ? options.onBasemapChange : null;
 
             this._injectStyles();
             this._handleOutsideClick = this._handleOutsideClick.bind(this);
@@ -442,13 +443,26 @@
             this.popover = this._createPopover();
             map.getContainer().appendChild(this.popover);
 
-            // Initialize active basemap on map load
-            if (map.loaded()) {
+            // Initialize active basemap on map load (checking map._loaded, isStyleLoaded, or loaded)
+            const isMapReady = Boolean(
+                map._loaded ||
+                (typeof map.isStyleLoaded === 'function' && map.isStyleLoaded()) ||
+                map.loaded()
+            );
+
+            if (isMapReady) {
                 this._applyInitialBasemap();
             } else {
-                map.on('load', () => this._applyInitialBasemap());
+                map.once('load', () => this._applyInitialBasemap());
             }
 
+            // Re-apply if the style reloads dynamically
+            map.on('style.load', () => {
+                if (this.activeBasemapId && this.activeBasemapId !== 'default') {
+                    this._applyInitialBasemap();
+                }
+            });
+
             document.addEventListener('click', this._handleOutsideClick);
 
             return this.container;
@@ -660,8 +674,11 @@
         }
 
         selectBasemap(id) {
+            const previousId = this.activeBasemapId;
             this.activeBasemapId = id;
-            localStorage.setItem('loko_active_basemap', id);
+            try {
+                localStorage.setItem('loko_active_basemap', id);
+            } catch (e) {}
 
             // Update UI list items
             if (this.popover) {
@@ -682,9 +699,20 @@
                     this._applyRasterBasemap(bgConfig);
                 }
             }
+
+            if (this.onBasemapChange && previousId !== id) {
+                try {
+                    this.onBasemapChange(id);
+                } catch (err) {
+                    console.error('[LayerSwitcherControl] onBasemapChange error:', err);
+                }
+            }
         }
 
         _applyInitialBasemap() {
+            if (!this.basemaps || this.basemaps.length === 0) {
+                this.basemaps = this._resolveBasemaps();
+            }
             if (this.activeBasemapId && this.activeBasemapId !== 'default') {
                 const bgConfig = this.basemaps.find(b => b.id === this.activeBasemapId);
                 if (bgConfig) {
@@ -693,13 +721,15 @@
                     return;
                 }
             }
-            // Check if any basemap has is_default
-            const defaultBg = this.basemaps.find(b => b.is_default);
-            if (defaultBg) {
-                this.selectBasemap(defaultBg.id);
-            } else {
-                this._updateButtonState();
+            // Check if any basemap has is_default only if activeBasemapId is not set
+            if (!this.activeBasemapId) {
+                const defaultBg = this.basemaps.find(b => b.is_default);
+                if (defaultBg) {
+                    this.selectBasemap(defaultBg.id);
+                    return;
+                }
             }
+            this._updateButtonState();
         }
 
         _removeCurrentRasterLayer() {
diff --git a/loko/common/tests.py b/loko/common/tests.py
index f0ab794..48fbb8e 100644
--- a/loko/common/tests.py
+++ b/loko/common/tests.py
@@ -324,6 +324,35 @@ class AssetsIndexPreferencesTests(TestCase):
         self.assertEqual(response.status_code, 400)
         self.assertIn("error", response.json())
 
+    def test_save_assets_index_preferences_with_basemap(self):
+        self.client.force_login(self.superuser)
+        save_url = reverse("common:save_assets_index_preferences")
+        payload = {
+            "thematics": ["sign"],
+            "basemap": "urbis_ortho",
+        }
+        response = self.client.post(save_url, json.dumps(payload), content_type="application/json")
+        self.assertEqual(response.status_code, 200)
+        self.assertTrue(response.json().get("success"))
+
+        from common.models import UserConfig
+        config = UserConfig.objects.get(user=self.superuser)
+        self.assertEqual(
+            config.assets_index_preferences.get("basemap"),
+            "urbis_ortho"
+        )
+
+    def test_save_assets_index_preferences_invalid_basemap_returns_400(self):
+        self.client.force_login(self.superuser)
+        save_url = reverse("common:save_assets_index_preferences")
+        payload = {
+            "basemap": 9999,
+        }
+        response = self.client.post(save_url, json.dumps(payload), content_type="application/json")
+        self.assertEqual(response.status_code, 400)
+        self.assertIn("error", response.json())
+
+
 
 
 class UserConfigCopyTests(TestCase):
diff --git a/loko/common/views.py b/loko/common/views.py
index 1683737..c5c7cec 100644
--- a/loko/common/views.py
+++ b/loko/common/views.py
@@ -663,6 +663,7 @@ def save_assets_index_preferences(request):
     include_no_geom = data.get('include_no_geom', True)
     map_center = data.get('map_center')
     map_zoom = data.get('map_zoom')
+    basemap = data.get('basemap')
 
     if not isinstance(thematics, list):
         return JsonResponse({'error': _('Format de thématiques invalide')}, status=400)
@@ -680,13 +681,18 @@ def save_assets_index_preferences(request):
         return JsonResponse({'error': _('Format de filtres statut invalide')}, status=400)
     if not isinstance(validation_status_filters, list):
         return JsonResponse({'error': _('Format de filtres statut de validation invalide')}, status=400)
+    if basemap is not None and not isinstance(basemap, str):
+        return JsonResponse({'error': _('Format de fond de plan invalide')}, status=400)
 
     try:
         user_config, _created = UserConfig.objects.get_or_create(user=request.user)
         existing_prefs = user_config.assets_index_preferences or {}
-        existing_visible_columns = existing_prefs.get('visible_columns', []) if isinstance(existing_prefs, dict) else []
+        if not isinstance(existing_prefs, dict):
+            existing_prefs = {}
+        existing_visible_columns = existing_prefs.get('visible_columns', [])
         if not isinstance(existing_visible_columns, list):
             existing_visible_columns = []
+        existing_basemap = existing_prefs.get('basemap', 'default')
 
         user_config.assets_index_preferences = {
             'thematics': thematics,
@@ -700,6 +706,7 @@ def save_assets_index_preferences(request):
             'include_no_geom': include_no_geom,
             'map_center': map_center,
             'map_zoom': map_zoom,
+            'basemap': basemap if basemap is not None else existing_basemap,
         }
         user_config.save(update_fields=['assets_index_preferences'])
         return JsonResponse({'success': True})