The team did not disclose terms of the deal.
Thomas, a 6-0, 200-pound cornerback from Southern California, was taken by the Giants with the 63rd overall selection in the draft. At USC, he played in 39 games with 28 starts. He had 109 tackles and eight interceptions.
Added were Shane Olivea of Ohio State and Jonathan Palmer of Auburn. The team waived Brandon Torrey, Dylan Thiry and Andrew Bain.