diff --git a/Userland/Libraries/LibGUI/VimEditingEngine.cpp b/Userland/Libraries/LibGUI/VimEditingEngine.cpp
index a12887a036..3d586f13a2 100644
--- a/Userland/Libraries/LibGUI/VimEditingEngine.cpp
+++ b/Userland/Libraries/LibGUI/VimEditingEngine.cpp
@@ -1411,4 +1411,19 @@ void VimEditingEngine::move_to_next_empty_lines_block()
     m_editor->set_cursor(new_cursor);
 };
 
+void VimEditingEngine::casefold_selection(Casing casing)
+{
+    VERIFY(!m_editor.is_null());
+    VERIFY(m_editor->has_selection());
+
+    switch (casing) {
+    case Casing::Uppercase:
+        m_editor->insert_at_cursor_or_replace_selection(m_editor->selected_text().to_uppercase());
+        return;
+    case Casing::Lowercase:
+        m_editor->insert_at_cursor_or_replace_selection(m_editor->selected_text().to_lowercase());
+        return;
+    }
+}
+
 }
diff --git a/Userland/Libraries/LibGUI/VimEditingEngine.h b/Userland/Libraries/LibGUI/VimEditingEngine.h
index b7216d0892..d9e956524a 100644
--- a/Userland/Libraries/LibGUI/VimEditingEngine.h
+++ b/Userland/Libraries/LibGUI/VimEditingEngine.h
@@ -160,6 +160,11 @@ private:
         Selection
     };
 
+    enum class Casing {
+        Uppercase,
+        Lowercase
+    };
+
     VimMode m_vim_mode { VimMode::Normal };
     VimMotion m_motion;
 
@@ -188,6 +193,8 @@ private:
     bool on_key_in_normal_mode(KeyEvent const& event);
     bool on_key_in_visual_mode(KeyEvent const& event);
 
+    void casefold_selection(Casing);
+
     virtual EngineType engine_type() const override { return EngineType::Vim; }
 };