WatchOS 27 introduces Siri AI on-device and a revamped Dynamic App Grid that highlights five Siri-suggested apps, with a new Siri app front and center and an emphasis on smarter personalization across the interface.

The update brings fitness and sleep enhancements, including Workout Buddy with data-driven motivation, improved indoor run/walk distance tracking, more accurate treadmill distance via ML, and updated sleep tracking accuracy.

Users gain expanded health features, notably enhanced women’s health tracking in Cycle Tracking for perimenopause and menopause, plus cycle deviation notifications tied to perimenopause changes.

Availability is staged: developer beta is live, public beta expected next month, with a general free rollout to eligible devices anticipated in September.

Series 9 was initially omitted due to a website error but is confirmed as supported in the final listing.

Earlier WatchOS versions like WatchOS 26 will likely receive security-only updates for devices unable to upgrade, though exact timelines remain unconfirmed.

Smart Stack gains context-aware capabilities, delivering timely, personalized prompts such as reminders for parked cars, birthday messages, or theatre mode based on location and activity.

Find My consolidates Find Devices, Find Items, and Find People into a single redesigned interface.

Workout Buddy provides progress-driven motivation and can operate without an iPhone, with expansion to Spanish for personalized prompts.

Other capabilities include more accurate treadmill distance, Wallet transit card pinning, and the ability to create customized passes with barcodes/QR codes for Smart Stack.

A new one-handed Smart Stack interaction allows a double-tap to open a widget, single-tap to choose, and a wrist-flick to return to the watch face.

Compatibility notes: watchOS 27 supports Apple Watch Ultra 3/2, Series 11/10/9, and Watch SE (3rd gen), with iPhone compatibility limited to iPhone 11–17 and iPhone SE (2nd/3rd gen) on iOS 27; a Series 9 paired with iPhone 16 is required for the upgrade.