After recovering from knee and ankle injuries, Roberson had 11 tackles and broke up three passes in seven games this season. He had 56 tackles, 17 pass breakups and three interceptions in his career.
ESPN's Todd McShay and Scouts Inc. consider Roberson to be a likely late-first-round pick in the May draft.
"I'm very thankful of everyone at Florida that helped me to get to this point in my career, from Tony Meacham, my academic adviser, to Jeff Dillman to Coach Muschamp and the entire coaching staff," Roberson said in a statement released by the Gators. "It's been a great experience here, and now that it is over I can truly appreciate everything that is in place here for players to be successful and have an opportunity to play at the next level."
Roberson was an All-SEC second-team selection in 2012.
The move leaves Florida extremely thin at cornerback. Roberson is the second Florida corner to declare early for the draft this year after Loucheiz Purifoy said he will turn pro in November. Defensive tackle Dominique Easley has also said he is leaving Florida early to enter the draft.
"Marcus has informed me that he has made the decision to pursue his dream of playing in the NFL," Florida coach Will Muschamp said. "Marcus was part of our first recruiting class, and it was a pleasure watching him mature and develop both on and off the field during his time here. I look forward to watching him play on Sundays, and like all of our players, I encourage them to return to complete his degree."