Milliner injured a tendon in his right wrist during practice on Thursday. He had just been medically cleared and returned to team practices on Aug. 1 for the first time since tearing his Achilles tendon last October.
The 23-year-old Milliner was limited to three games last season due to injury.
As a rookie in 2013, Milliner recorded 56 tackles and three interceptions in 13 games. He was the No. 9 pick in the 2013 NFL draft.
The Jets open the regular season on Sept. 13 at home against the Cleveland Browns.
- Molly Geary