Boldin finished with five catches for 94 yards and two touchdowns — a 19-yard grab at the pylon in the first quarter and a 6-yard, wide-open-in-the-end-zone reception in the third.
Vernon Davis also had a touchdown catch for the 49ers (7-4), who are tied for second with the Arizona Cardinals in the NFC West and are three games back of the Seattle Seahawks with five to play.
"We knew what type of game this was for us. We're right in the hunt," Boldin said. "We've got to come out with a win."
A loss would've put the defending NFC champions in trouble in their quest to return to the playoffs, but they're nowhere as bad off as the Redskins (3-8), who have dropped three straight and sit alone in last place in the NFC East a year after a late-season run that won the division.
Kaepernick and Griffin seemed poised to take the quarterback position to a new dimension last season when they wowed the NFL with their mobility when running zone-read and play-action.
But defenses have adjusted, and the two QBs' stats have tumbled accordingly when they've been forced to throw in conventional drop-back situations.
Griffin's fall has been more precipitous. He threw his 11th interception Monday night, more than twice the number he had all last season.
He completed 17 of 27 passes for 127 yards and was sacked four times, and Washington tallied only 190 total yards. RG3's throws were off-target, and the Redskins were again the victim of questionable clock management, including a timeout that was called while the clock was already stopped on a hurry-up drive in the final minute of the first half.
The 49ers led 10-6 at the half, and the Redskins had their best chance to take the lead when they took over in San Francisco territory after a fumble on the opening drive of the third quarter. But, on a fourth-and-2 at the 41, Washington gave the ball to backup tailback Roy Helu, who was stopped short of the first down.
The 49ers took over and drove for a score that gave them a double-digit lead for good, with Kaepernick and Boldin hurdling into each other for a celebratory chest-bump after the 6-yard touchdown pass.