The 25-year-old Delmas returns to Detroit after the Lions added free-agent safety Glover Quin earlier this week.
Delmas played only eight games last season but started them all. He was limited by left knee problems. He's started 49 games in four seasons with the Lions.
The secondary has been a spot of instability for the Lions, but they've acquired Quin and retained free agent defensive backs Delmas and Chris Houston.
Detroit also signed running back Reggie Bush this week to bolster the offense.
Information from ESPN NFL Insider Adam Schefter and The Associated Press was used in this report.