Smith was widely considered one of the top receivers in free agency and could be a good fit for Colin Kaepernick, the team's strong armed quarterback.
Smith was with the Ravens since being selected in the second round of the 2011 NFL Draft. He has recorded 213 receptions for 3,591 yards and 30 receiving touchdowns in his 62 starts out of 64 games in his career.
Smith and Boldin helped the Ravens defeat the 49ers in Super Bowl XLVII.
It was reported earlier today that Boldin played a big part in getting Smith to San Francisco. He helped the 49ers in the recruitment process.