That year, he was named an Associated Press Big School second-team all-state, Baltimore Sun honorable mention All-Met, and all-county player.

Barnes redshirted in 2004 and was named the defensive scout team player of the week prior to the NC State and Virginia Tech games.

After the 2007 season, the Terrapins lost three starters in the secondary to graduation, and Barnes stepped in to assume a leadership role during his senior year.

[6] In the third game of the season, against California, Barnes gained notoriety for the delivery of a hard hit against running back Jahvid Best, an early Heisman Trophy prospect.

Footage of the hit and its aftermath circulated widely on the internet and became a viral video phenomenon that received 50,000 views on YouTube within a week.

In the seventh game of the season, he used his left shoulder to hit Wake Forest wide receiver D. J. Boldin, who was attempting to catch a pass.

[9] Barnes suffered a torn glenoid labrum, fractured left scapula, damaged rotator cuff, and broken clavicle.

"[12] Despite being unable to play, Barnes remained actively involved with the Terrapins for the rest of the season and took on the role of a student coach.

All throughout the game in the pouring rain against NC State, he was talking to the guys on the sideline, so he's like another coach.... We all miss having him on the field, but we're glad he's still with us in some capacity.

"Barnes received an unusually early invitation to the 2009 Senior Bowl, on September 18, just five days after the game against California in which he tackled Best.

[22] Regarding his offseason performance, the club's executive vice president, Vinny Cerrato, said, "It was like a light came on, so Kevin was just playing instead of thinking all the time....

[22] In camp before the 2010 season, Barnes and veteran cornerback Phillip Buchanon out-performed Tryon, who was eventually traded to the Indianapolis Colts.

[23] At the start of the season, with Zorn replaced by Mike Shanahan as head coach, Barnes and linebacker Brian Orakpo were the only players retained from the 2009 draft class.

[24] Against the Jacksonville Jaguars, Barnes started as a safety alongside Macho Harris because of injuries suffered by LaRon Landry, Kareem Moore, and Reed Doughty.

Kevin Barnes intercepted a pass thrown by Tony Romo on Monday Night Football in a Redskins loss (18–16) against the Dallas Cowboys.

Despite being used as a nickelback last season, it was reported that Barnes has been taking snaps at both the free safety and outside cornerback positions in the 2012 off-season under new defensive backs coach, Raheem Morris.

[31] With DeAngelo Hall taking over the nickelback position, he competed with and lost to the Redskins' free agent acquisition, Cedric Griffin, for the second outside cornerback slot opposite to starter, Josh Wilson.