Boldin has totaled 20 receptions and averaged 95.0 yards in his last three games.
The 49ers poor passing attack has hurt Boldin's numbers in recent weeks, as his six catches versus New Orleans was his most i a game since his 13 grabs versus Green Bay in the season opener.
He came within nine yards of his career best total. While with Arizona, Boldin had 10 catches for 217 yards and two scores at Detroit on Sept. 7, 2003.
The deal, announced by the team shortly after the start of the free agency period Tuesday, is pending a physical. Boldin was a big key in Baltimore's 34-31 Super Bowl victory against the 49ers. He made six catches for 104 yards and a touchdown and also had five receptions for 60 yards and two TDs in a victory over New England in the AFC title game.
Boldin, a star in Baltimore's run to the Super Bowl title last season, must pass a physical to complete the deal. The Ravens announced the trade Monday. Boldin had six catches for 104 yards and a touchdown in the Ravens' 34-31 Super Bowl victory over the 49ers. The 32-year-old Boldin had said he'd consider retirement rather than leave Baltimore. But going to the NFC champions might change his mind.