diff --git a/distribution/openrct2.d.ts b/distribution/openrct2.d.ts
index a4ea761a93..998f3bb311 100644
--- a/distribution/openrct2.d.ts
+++ b/distribution/openrct2.d.ts
@@ -412,6 +412,7 @@ declare global {
         minWidth?: number;
         minHeight?: number;
         widgets?: Widget[];
+        colours?: number[];
         tabs?: Tab[];
 
         onClose?: () => void;
diff --git a/src/openrct2-ui/scripting/CustomWindow.cpp b/src/openrct2-ui/scripting/CustomWindow.cpp
index 2d9aebd440..a79cf825db 100644
--- a/src/openrct2-ui/scripting/CustomWindow.cpp
+++ b/src/openrct2-ui/scripting/CustomWindow.cpp
@@ -207,6 +207,7 @@ namespace OpenRCT2::Ui::Windows
         std::string Title;
         std::optional<int32_t> Id;
         std::vector<CustomWidgetDesc> Widgets;
+        std::vector<colour_t> Colours;
 
         CustomWindowDesc() = default;
 
@@ -238,6 +239,19 @@ namespace OpenRCT2::Ui::Windows
                 });
             }
 
+            if (desc["colours"].is_array())
+            {
+                auto dukColours = desc["colours"].as_array();
+                std::transform(dukColours.begin(), dukColours.end(), std::back_inserter(result.Colours), [](const DukValue& w) {
+                    colour_t c = COLOUR_BLACK;
+                    if (w.type() == DukValue::Type::NUMBER)
+                    {
+                        c = static_cast<colour_t>(std::clamp<int32_t>(w.as_int(), COLOUR_BLACK, COLOUR_COUNT - 1));
+                    }
+                    return c;
+                });
+            }
+
             return result;
         }
 
@@ -315,9 +329,17 @@ namespace OpenRCT2::Ui::Windows
         window->number = GetNewWindowNumber();
         window->custom_info = new CustomWindowInfo(owner, desc);
         window->enabled_widgets = (1 << WIDX_CLOSE);
+
+        // Set window colours
         window->colours[0] = COLOUR_GREY;
         window->colours[1] = COLOUR_GREY;
         window->colours[2] = COLOUR_GREY;
+        auto numColours = std::min(std::size(window->colours), std::size(desc.Colours));
+        for (size_t i = 0; i < numColours; i++)
+        {
+            window->colours[i] = desc.Colours[i];
+        }
+
         if (desc.IsResizable())
         {
             window->min_width = desc.MinWidth.value_or(0);
diff --git a/src/openrct2-ui/scripting/ScWindow.hpp b/src/openrct2-ui/scripting/ScWindow.hpp
index 490a38fe08..7c81653972 100644
--- a/src/openrct2-ui/scripting/ScWindow.hpp
+++ b/src/openrct2-ui/scripting/ScWindow.hpp
@@ -98,6 +98,33 @@ namespace OpenRCT2::Scripting
             return result;
         }
 
+        std::vector<int32_t> colours_get()
+        {
+            std::vector<int32_t> result;
+            auto w = GetWindow();
+            if (w != nullptr)
+            {
+                result.reserve(std::size(w->colours));
+                for (auto c : w->colours)
+                {
+                    result.push_back(c);
+                }
+            }
+            return result;
+        }
+        void colours_set(std::vector<int32_t> colours)
+        {
+            auto w = GetWindow();
+            if (w != nullptr)
+            {
+                for (int32_t i = 0; i < std::size(w->colours); i++)
+                {
+                    w->colours[i] = i < colours.size() ? std::clamp<int32_t>(colours[i], COLOUR_BLACK, COLOUR_COUNT - 1)
+                                                       : COLOUR_BLACK;
+                }
+            }
+        }
+
         void close()
         {
             auto w = GetWindow();
@@ -141,6 +168,7 @@ namespace OpenRCT2::Scripting
             dukglue_register_property(ctx, &ScWindow::height_get, nullptr, "height");
             dukglue_register_property(ctx, &ScWindow::isSticky_get, nullptr, "isSticky");
             dukglue_register_property(ctx, &ScWindow::widgets_get, nullptr, "widgets");
+            dukglue_register_property(ctx, &ScWindow::colours_get, &ScWindow::colours_set, "colours");
 
             dukglue_register_method(ctx, &ScWindow::close, "close");
             dukglue_register_method(ctx, &ScWindow::findWidget, "findWidget");