Running a MacBook with the laptop display off

In a nutshell, here’s how to run a MacBook with just an external display:

  1. With your MacBook on and running, plug in your external monitor and turn it on
  2. Make sure the MacBook display is in mirror mode.
  3. Close your MacBook. The whole system (including external display will go to sleep).
  4. Plug a USB device into the MacBook (e.g. your mouse) to bring it out of sleep
  5. Open up your MacBook. The display will be off.