Selected 11th overall out of Troy University, McKelvin signed his rookie contract at the Bills headquarters in Orchard Park and was preparing to join the team at its training camp facility in suburban Rochester after he missed four practices, including two on Saturday.
Shortly after McKelvin's agent, Hadley Engelhard, told The Associated Press that his client had agreed to a deal, the Bills announced that the player had signed his contract.
McKelvin was the first defensive back selected in the draft, and will compete with Jabari Greer for a starting job opposite Terrence McGee this season.
Under terms of the deal, McKelvin is guaranteed $12.6 million, and would have to meet all of his incentive clauses to earn the contract's full value.
McKelvin had been only one of four first-round draft picks yet to sign with their respective teams.
McKelvin, from Waycross, Ga., was a two-year starter and regarded as the most athletic cornerback in this year's draft class. He possesses great speed, is solid in coverage and a sure tackler. McKelvin also is a double-threat on special teams; his eight career returns for touchdowns (seven punts and one kickoff) tied the NCAA Division I-A record.
As a cornerback, he finished his college career with only four interceptions, but proved solid in defending opponents' top receivers.
Last year, McKelvin had six tackles, forced a fumble and broke up three passes in a game against Florida. Two years ago, McKelvin limited Georgia Tech's Calvin Johnson - the second pick in last year's NFL Draft - to two catches for 9 yards. The only knock against McKelvin has been that he's dropped some potential interceptions.
"It's hard to catch up. Hopefully, he'll be in as soon as he's able to be here," Jauron said. "Every practice is significant. ... We can spend extra time with him, but there are reps that just keep going by."