Turn on your iPhone and Apple Watch
Keep both devices close together
Make sure Bluetooth is turned on
Make sure your iPhone is connected to Wi-Fi or cellular data
Open the Apple Watch app on your iPhone
Tap Start Pairing
Hold the Apple Watch over the animation on your iPhone
Follow the on-screen setup steps
Choose Restore from Backup or Set Up as New Apple Watch
Sign in with your Apple ID if prompted
Complete the settings for passcode, Siri, and app preferences
Wait for the sync to finish
Keep both devices near each other until pairing is complete