The Ravens did not specify the round for the pick on their Twitter account, but ESPN reported it to be a fourth-round selection.
Evans had spent his first seven NFL seasons in Buffalo, which selected him with the 13th overall pick of the 2004 draft. He is coming off a disappointing 2010 campaign, finishing with a career-low 37 catches and 578 yards in 13 games.
An ankle injury cost him the final three games last year, ending a streak of 109 straight games played.
The 30-year-old Wisconsin product has twice been a 1,000-yard receiver. He set career-highs of 82 receptions and 1,292 yards in 2006 and two years later also eclipsed the 1,000-yard plateau.
Evans has 377 catches for 5,934 yards with 43 touchdowns in his career.