The answer depends on which features matter to you.
For the core AirPods Pro 3 experience—noise cancellation, transparency mode, Adaptive Audio, Spatial Audio, heart rate monitoring, hearing aid features, and Find My—any iPhone running iOS 18 works. That includes iPhone XS and everything newer.
The one major exception is Live Translation. This feature requires an iPhone 15 Pro or later, because it uses Apple Intelligence for on-device processing. The A17 Pro chip (and newer) has the neural engine power to run translation models locally while keeping your conversations private. Older iPhones simply don't have the processing capacity.
Here's what that means practically:
If you have an iPhone 15 Pro, 16, or later, you get every feature. All the headline capabilities work, including real-time translation in English, French, German, Portuguese, and Spanish (with more languages coming).
If you have an iPhone 14, 13, 12, 11, or XS, you still get an excellent experience. Noise cancellation, heart rate monitoring, hearing aid features, Spatial Audio—all of it works. You just won't have Live Translation.
If you're on iPhone XS or XR specifically, you're at the minimum iOS 18 compatibility line. Everything works, but you might want to consider whether your phone's battery and overall performance are still holding up for daily use.
The iPad situation is similar: basic features work with iPadOS 18, but Live Translation needs an M-series iPad Pro or iPad Air running iPadOS 26.
For Mac users, AirPods Pro 3 pair and work for audio, ANC, and Spatial Audio with macOS Sonoma or later. Some configuration still requires an iPhone initially.