Fleming, selected 140th overall, had yet to join the Patriots as of Thursday because his class at Stanford had yet to graduate. But he was expected to be in town for this weekend's rookie minicamp.
Patriots coach Bill Belichick was complimentary of Fleming (6-foot-4 7/8, 323) after drafting him.
"He's a big kid who played against a lot of good competition," he said. "They run the ball a lot and they run a very conventional offense compared to what some of the offenses are in college football, so you can kind of see him do a lot of the things that we see in the National Football League."
Fleming becomes the second of the Patriots' nine draft picks to sign a contract, joining defensive end Zach Moore (sixth round, 198th overall). There are not expected to be any contractual-related issues with any of the draft picks.