Boldin repeatedly said during the offseason that he would not take a pay cut from the team. He signed a four-year, $28 million contract in 2010 and was due a $6 million salary this season.
Boldin, 32, needs to pass a physical before the trade with the 49ers becomes complete as he is in Africa doing charity work, ESPN.com reports.
Boldin helped the team to a Super Bowl victory this past season by leading all NFL receivers with 22 catches for 380 yards in the postseason, including six grabs for 104 yards and a touchdown during the Ravens' 34-31 victory over the 49ers in Super Bowl XLVII.
He had 65 catches for 921 yards and four touchdowns during the regular season.