Thomas' agent tweeted the signing.
Thomas joins defensive end Zach Moore, offensive tackle Cameron Fleming, receiver Jeremy Gallon and running back James White as Patriots draft picks to sign their rookie contracts. There are no anticipated delays with the team's other four picks -- defensive lineman Dominique Easley (first round), quarterback Jimmy Garoppolo (second round), center Bryan Stork (fourth round) and guard Jon Halapio (sixth round).
As for Thomas, Patriots coach Bill Belichick was complimentary of him on draft day.
"He played in a number of different spots -- in the kicking game, a little safety, a little nickel, some corner. It looks like he's got the ability to compete at all those spots," Belichick said. "Versatile guy, smart guy. Really a four-down type player. He's an interesting guy."