The 27-year-old Ratliff visited the Steelers in the past week and was interested in signing, but James Harrison's deal ate up most of Pittsburgh's remaining cap room. With the departure of Bryant McFadden in free agency, the Steelers had an opening for a veteran cornerback.
The agreement with Ratliff takes some pressure off the Steelers to select a cornerback in the first couple of rounds of the draft Saturday and Sunday.
Ratliff was a second-round choice of the Bengals in 2004. He started eight games in his first two seasons in Cincinnati, but he played primarily as a backup his final two years.
He went to the Tampa Bay Buccaneers in 2007 and landed with the Colts that year. Because of injuries in the secondary in 2008, Ratliff started four of the 13 games he played in Indianapolis.
Senior writer John Clayton covers the NFL for ESPN.com.