Can I use an iMac 24 inch early 2009 as a display for Mac mini?

No, you cannot use the old iMac as a directly connected display for the new Mac mini.

There is no longer an Apple supported option to use an iMac as a monitor with any computer.

You might consider a third-party solution - Luna Display or Duet Display - though I can’t speak for the performance of those. Regardless, you still will need a proper monitor to set up either of those options.

Do yourself a favor, avoid the headache and just budget an extra $100 for a monitor. Yes, they are that inexpensive.

Click here for information. If that configuration isn't supported, use a standalone monitor to set up Virtual Network Computing.

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