Bills general manager Buddy Nix expected the nose tackle to arrive at camp in suburban Rochester in time for the team's first practice Thursday afternoon.
At 6-foot-3 and 315 pounds, Troup was selected in the second round -- 41st overall -- out of Central Florida. He is a run-stuffer who helped the Golden Knights finish first in Conference USA and fourth in the nation by allowing just under 83 yards rushing last season.
Terms of the deal weren't immediately available, but it's expected to be for four years and worth about $4.5 million, with about $2.6 million guaranteed.
A two-time All-Conference selection, Troup is expected to compete for the backup job behind starter Kyle Williams as the Bills make the switch to a 3-4 defense this season.
The move leaves the Bills with one unsigned rookie, running back C.J. Spiller, who was drafted ninth overall out of Clemson.
Nix said he's had talks with Spiller's agent, but cautioned it's too early to tell when a deal could be reached. Spiller's agent, Gary Wichard, was unavailable.
One drawback to negotiations is establishing the parameters of a deal with Spiller because of the few first-round picks who have signed.
Also Wednesday, starting linebacker Paul Posluszny said he will be limited at the start of camp after having groin surgery two weeks ago. Posluszny described the procedure as minor after he was hurt during the team's offseason minicamps.
Posluszny expects to work out on his own and be limited to taking part only in team walkthroughs for the first few weeks. He said it was better to have the injury addressed now so he could be fully healthy for the start of the season.
"I feel like I was able to pick up the defense pretty well in minicamp, but I definitely need to be out there," he said. "I feel like I will be a little bit behind. But hopefully, I'll be able to catch up when I get back out there."
Backup safety Jon Corto will miss at least the first three weeks of camp after having surgery to repair a broken left wrist. Corto is still wearing a brace after he aggravated an earlier injury during minicamp last month.