Apple (release notes, security, developer):

Explore what’s new for watchOS 27.

See also:

• Juli Clover
• John Voorhees

Previously:

• watchOS 27 Announced
• watchOS 26

Update (2026-09-16): Sarah Reichelt:

If anyone like me is struggling to update their Apple Watch, the Install button in the Watch app scrolls almost off the bottom of the screen on my iPhone 17 Pro. You can just see a few orange pixels. Try to tap them and it should work.