How to use Secure Boot to make sure your iMac Pro boots up a legitimate OS

Secure Boot is a feature exclusive to the iMac Pro that lets your machine verify that it is booting a legitimate or supported version of macOS. Used through the iMac Pro's Startup Security Utility, Secure Boot offers different levels of protection based on your needs.

Secure Boot comes with three settings:

  • Full Security - Using this setting, the only operating systems that can boot on your iMac Pro are the version that is currently installed or a signed OS trusted by Apple.
  • Medium Security - Any signed version of an operating system trusted by Apple can run on your iMac Pro.
  • No Security - No requirements are enforced on on bootable operating systems.

Here's how you can use and manage Secure Boot on your iMac Pro.

How to use Secure Boot on the iMac Pro

To use Secure Boot, you'll need to enter the iMac Pro's Startup Security Utility immediately upon startup of your machine.

  1. Immediately press Command (⌘) and R at the same time right after turning on your iMac Pro.
  2. Click Utilities in the Menu bar in the Utilities window.
  3. Click Startup Security Utility.
  4. Click Enter macOS Password when asked to authenticate.
  5. Select an administrator account.
  6. Enter the account password.
  7. Choose Full Security, Medium Security, and No Security.
  8. Close Security Startup Utility.
  9. Click the Apple icon in the Menu bar.
  10. Click Restart to restart your iMac Pro with your new security settings in place.


If you've got any further questions about using Secure Boot on the iMac Pro, ask away in the comments.

Joseph Keller

Joseph Keller is the former Editor in Chief of iMore. An Apple user for almost 20 years, he spends his time learning the ins and outs of iOS and macOS, always finding ways of getting the most out of his iPhone, iPad, Apple Watch, and Mac.