diff --git a/public/mainWindow.js b/public/mainWindow.js
index 223c7f8..e9b7f41 100644
--- a/public/mainWindow.js
+++ b/public/mainWindow.js
@@ -227,6 +227,12 @@ export function createWindow() {
   setupWindowEvents()
   attachKeyboardShortcuts(win)
   setupNavigationGestures(win)
+
+  if (process.platform === 'darwin') {
+    win.maximize()
+  } else if (process.platform === 'win32') {
+    win.setFullScreen(true)
+  }
 }
 
 export function getWindow() {
diff --git a/src/desktop/window.js b/src/desktop/window.js
index d4be591..8941bda 100644
--- a/src/desktop/window.js
+++ b/src/desktop/window.js
@@ -89,6 +89,18 @@ function broadcastWindowState() {
   sendToRenderer('windowState', getWindowState())
 }
 
+function applyStartupWindowState(window) {
+  if (!window) return
+
+  if (isMacOS) {
+    window.maximize?.()
+  } else if (process.platform === 'win32') {
+    window.setFullScreen?.(true)
+  }
+
+  setTimeout(broadcastWindowState, 100)
+}
+
 function setupWindowEvents(window) {
   // Electrobun emits resize/focus, not Electron's maximize/fullscreen events.
   window.on?.('resize', broadcastWindowState)
@@ -166,6 +178,7 @@ export async function createMainWindow(rpc) {
   })
 
   setupWindowEvents(mainWindow)
+  applyStartupWindowState(mainWindow)
 
   Electrobun.events.on('open-url', (event) => {
     const url = event?.data?.url