diff --git a/Userland/Applications/ThemeEditor/PreviewWidget.cpp b/Userland/Applications/ThemeEditor/PreviewWidget.cpp
index 0c2fe956b6..cc4f2696fc 100644
--- a/Userland/Applications/ThemeEditor/PreviewWidget.cpp
+++ b/Userland/Applications/ThemeEditor/PreviewWidget.cpp
@@ -97,6 +97,16 @@ void PreviewWidget::set_preview_palette(const Gfx::Palette& palette)
     update();
 }
 
+void PreviewWidget::set_theme_from_file(String const& path, int fd)
+{
+    auto file = Core::ConfigFile::open(path, fd);
+    auto theme = Gfx::load_system_theme(file);
+    VERIFY(theme.is_valid());
+
+    m_preview_palette = Gfx::Palette(Gfx::PaletteImpl::create_with_anonymous_buffer(theme));
+    set_preview_palette(m_preview_palette);
+}
+
 void PreviewWidget::paint_event(GUI::PaintEvent& event)
 {
     GUI::Frame::paint_event(event);
diff --git a/Userland/Applications/ThemeEditor/PreviewWidget.h b/Userland/Applications/ThemeEditor/PreviewWidget.h
index 2a1ab0ca9e..10be2f0339 100644
--- a/Userland/Applications/ThemeEditor/PreviewWidget.h
+++ b/Userland/Applications/ThemeEditor/PreviewWidget.h
@@ -21,6 +21,7 @@ public:
 
     const Gfx::Palette& preview_palette() const { return m_preview_palette; }
     void set_preview_palette(const Gfx::Palette&);
+    void set_theme_from_file(String const& path, int fd);
 
 private:
     explicit PreviewWidget(const Gfx::Palette&);
diff --git a/Userland/Applications/ThemeEditor/main.cpp b/Userland/Applications/ThemeEditor/main.cpp
index 4b8444ddbe..56f181d5e5 100644
--- a/Userland/Applications/ThemeEditor/main.cpp
+++ b/Userland/Applications/ThemeEditor/main.cpp
@@ -143,6 +143,14 @@ int main(int argc, char** argv)
         theme->sync();
     };
 
+    file_menu.add_action(GUI::CommonActions::make_open_action([&](auto&) {
+        auto result = FileSystemAccessClient::Client::the().open_file(window->window_id(), "Select theme file", "/res/themes");
+        if (result.error != 0)
+            return;
+
+        preview_widget.set_theme_from_file(*result.chosen_file, *result.fd);
+    }));
+
     file_menu.add_action(GUI::CommonActions::make_save_action([&](auto&) {
         if (path.has_value()) {
             save_to_result(FileSystemAccessClient::Client::the().request_file(window->window_id(), *path, Core::OpenMode::WriteOnly | Core::OpenMode::Truncate));