diff --git a/source/blender/editors/space_outliner/tree/tree_element.cc b/source/blender/editors/space_outliner/tree/tree_element.cc
index 19eb5d6d558..d8a583e321c 100644
--- a/source/blender/editors/space_outliner/tree/tree_element.cc
+++ b/source/blender/editors/space_outliner/tree/tree_element.cc
@@ -198,7 +198,9 @@ std::unique_ptr<AbstractTreeElement> AbstractTreeElement::create_from_type(const
           legacy_te, *reinterpret_cast<bArmature *>(owner_id));
     case TSE_BONE_COLLECTION:
       return std::make_unique<TreeElementBoneCollection>(
-          legacy_te, *static_cast<BoneCollection *>(create_data));
+          legacy_te,
+          *reinterpret_cast<bArmature *>(owner_id),
+          *static_cast<BoneCollection *>(create_data));
 
     default:
       break;
diff --git a/source/blender/editors/space_outliner/tree/tree_element_bone_collection.cc b/source/blender/editors/space_outliner/tree/tree_element_bone_collection.cc
index d7feb7a8316..f82f97d464d 100644
--- a/source/blender/editors/space_outliner/tree/tree_element_bone_collection.cc
+++ b/source/blender/editors/space_outliner/tree/tree_element_bone_collection.cc
@@ -30,19 +30,32 @@ TreeElementBoneCollectionBase::TreeElementBoneCollectionBase(TreeElement &legacy
 
 void TreeElementBoneCollectionBase::expand(SpaceOutliner & /*space_outliner*/) const
 {
-  for (int index = 0; index < armature_.collection_array_num; index++) {
-    BoneCollection *bcoll = armature_.collection_array[index];
+  int index = 0;
+  for (BoneCollection *bcoll : armature_.collections_roots()) {
     add_element(
         &legacy_te_.subtree, &armature_.id, bcoll, &legacy_te_, TSE_BONE_COLLECTION, index);
+    index++;
   }
 }
 
-TreeElementBoneCollection::TreeElementBoneCollection(TreeElement &legacy_te, BoneCollection &bcoll)
-    : AbstractTreeElement(legacy_te), bcoll_(bcoll)
+TreeElementBoneCollection::TreeElementBoneCollection(TreeElement &legacy_te,
+                                                     bArmature &armature,
+                                                     BoneCollection &bcoll)
+    : AbstractTreeElement(legacy_te), armature_(armature), bcoll_(bcoll)
 {
   BLI_assert(legacy_te.store_elem->type == TSE_BONE_COLLECTION);
   legacy_te.name = bcoll_.name;
   legacy_te.directdata = &bcoll_;
 }
 
+void TreeElementBoneCollection::expand(SpaceOutliner & /*space_outliner*/) const
+{
+  int index = 0;
+  for (BoneCollection *child_bcoll : armature_.collection_children(&bcoll_)) {
+    add_element(
+        &legacy_te_.subtree, &armature_.id, child_bcoll, &legacy_te_, TSE_BONE_COLLECTION, index);
+    index++;
+  }
+}
+
 }  // namespace blender::ed::outliner
diff --git a/source/blender/editors/space_outliner/tree/tree_element_bone_collection.hh b/source/blender/editors/space_outliner/tree/tree_element_bone_collection.hh
index bbfdf651ba0..3c3205852af 100644
--- a/source/blender/editors/space_outliner/tree/tree_element_bone_collection.hh
+++ b/source/blender/editors/space_outliner/tree/tree_element_bone_collection.hh
@@ -24,10 +24,12 @@ class TreeElementBoneCollectionBase final : public AbstractTreeElement {
 };
 
 class TreeElementBoneCollection final : public AbstractTreeElement {
+  bArmature &armature_;
   BoneCollection &bcoll_;
 
  public:
-  TreeElementBoneCollection(TreeElement &legacy_te, BoneCollection &bcoll);
+  TreeElementBoneCollection(TreeElement &legacy_te, bArmature &armature, BoneCollection &bcoll);
+  void expand(SpaceOutliner &) const override;
 };
 
 }  // namespace blender::ed::outliner