watchOS 6.3.1 (build 17U224) is an official Apple over-the-air update for the Apple Watch Series 5 (44mm, LTE), released on 2026-02-02T18:44:53Z. The update package is 318.98 MB. This is a delta (partial) update that requires 6.2.1 already installed. This update is currently signed by Apple, so it can be applied from Settings › General › Software Update.

Payload file: f9a2c017a879046f4c5a4b428e1a6e1683be5052.zip.