diff --git a/Code/Editor/Plugins/ComponentEntityEditorPlugin/UI/Outliner/OutlinerSortFilterProxyModel.cpp b/Code/Editor/Plugins/ComponentEntityEditorPlugin/UI/Outliner/OutlinerSortFilterProxyModel.cpp
index 660ea137cf..89cd361fb6 100644
--- a/Code/Editor/Plugins/ComponentEntityEditorPlugin/UI/Outliner/OutlinerSortFilterProxyModel.cpp
+++ b/Code/Editor/Plugins/ComponentEntityEditorPlugin/UI/Outliner/OutlinerSortFilterProxyModel.cpp
@@ -32,7 +32,24 @@ bool OutlinerSortFilterProxyModel::filterAcceptsRow(int sourceRow, const QModelI
 
 bool OutlinerSortFilterProxyModel::lessThan(const QModelIndex& leftIndex, const QModelIndex& rightIndex) const
 {
-    return sourceModel()->data(leftIndex).toString() < sourceModel()->data(rightIndex).toString();
+    if (leftIndex.isValid() && rightIndex.isValid())
+    {
+        QVariant leftData = sourceModel()->data(leftIndex);
+        QVariant rightData = sourceModel()->data(rightIndex);
+
+        // make sure to compare the correct data types for sorting the current column
+        AZ_Assert(leftData.type() == rightData.type(), "OutlinerSortFilterProxyModel::lessThan types do not agree!");
+        if (static_cast<QMetaType::Type>(leftData.type()) == QMetaType::QString)
+        {
+            return leftData.toString() < rightData.toString();
+        }
+        else if (static_cast<QMetaType::Type>(leftData.type()) == QMetaType::ULongLong)
+        {
+            return leftData.toULongLong() < rightData.toULongLong();
+        }
+        AZ_Error("Editor", false, "Error! Unhandled type \"%s\" in OutlinerSortFilterProxyModel::lessThan", leftData.typeName());
+    }
+    return false;
 }
 
 void OutlinerSortFilterProxyModel::sort(int /*column*/, Qt::SortOrder /*order*/)
diff --git a/Code/Framework/AzToolsFramework/AzToolsFramework/UI/Outliner/EntityOutlinerSortFilterProxyModel.cpp b/Code/Framework/AzToolsFramework/AzToolsFramework/UI/Outliner/EntityOutlinerSortFilterProxyModel.cpp
index 73139b5a67..90274bc734 100644
--- a/Code/Framework/AzToolsFramework/AzToolsFramework/UI/Outliner/EntityOutlinerSortFilterProxyModel.cpp
+++ b/Code/Framework/AzToolsFramework/AzToolsFramework/UI/Outliner/EntityOutlinerSortFilterProxyModel.cpp
@@ -34,7 +34,24 @@ namespace AzToolsFramework
 
     bool EntityOutlinerSortFilterProxyModel::lessThan(const QModelIndex& leftIndex, const QModelIndex& rightIndex) const
     {
-        return sourceModel()->data(leftIndex).toString() < sourceModel()->data(rightIndex).toString();
+        if (leftIndex.isValid() && rightIndex.isValid())
+        {
+            QVariant leftData = sourceModel()->data(leftIndex);
+            QVariant rightData = sourceModel()->data(rightIndex);
+
+            // make sure to compare the correct data types for sorting the current column
+            AZ_Assert(leftData.type() == rightData.type(), "EntityOutlinerSortFilterProxyModel::lessThan types do not agree!");
+            if (static_cast<QMetaType::Type>(leftData.type()) == QMetaType::QString)
+            {
+                return leftData.toString() < rightData.toString();
+            }
+            else if (static_cast<QMetaType::Type>(leftData.type()) == QMetaType::ULongLong)
+            {
+                return leftData.toULongLong() < rightData.toULongLong();
+            }
+            AZ_Error("Editor", false, "Error! Unhandled type \"%s\" in EntityOutlinerSortFilterProxyModel::lessThan", leftData.typeName());
+        }
+        return false;
     }
 
     void EntityOutlinerSortFilterProxyModel::sort(int /*column*/, Qt::SortOrder /*order*/)