Apple's watchOS 27 will only run on five specific Apple Watch models, leaving some relatively recent devices incompatible. The compatible lineup includes the Apple Watch SE 3, Apple Watch Series 10, Series 11, Ultra 2, and Ultra 3. Notably absent are the original Watch Ultra and SE 2, both released in 2022, which now face obsolescence just two years after launch.

This cutoff represents a tighter window than typical for Apple's wearable support. The Series 9 omission initially raised eyebrows given its 2023 release date, though Apple later confirmed it will receive the update. Still, dropping 2022 models while supporting older hardware suggests Apple Intelligence features may require more processing power than earlier watches can deliver.

The restriction contrasts sharply with iOS 27's broader compatibility, extending back to the iPhone 11. Apple appears to be prioritizing AI capabilities over extended hardware support, potentially fragmenting the user experience across its ecosystem.

Apple's website still shows the incomplete compatibility list, suggesting a rushed announcement. For consumers, this means planning upgrades sooner than expected, while developers must account for fewer supported devices when building watchOS applications.