Wilcox was due a non-guaranteed salary of $3.125 million, and releasing him leaves $625,000 in dead money on the cap.
In 2017, Wilcox played in 12 games, including one start, and finished with one interception, one pass defensed and 12 tackles for Pittsburgh.
He started all 16 regular-season games plus two postseason games for the Dallas Cowboys in 2014 and had 13 starts in 2015.
Pittsburgh acquired Wilcox from the Tampa Bay Buccaneers in September 2017 in a trade that sent Wilcox and a 2019 seventh-round draft pick to Pittsburgh in exchange for a sixth-round choice in the 2018 draft.
The Steelers selected two safeties in this year's draft -- first-round pick Terrell Edmunds and fifth-round pick Marcus Allen.