Kieran Millan stopped 29 shots and Wade Megan 1 decision over Harvard in the first semifinal matchup of the 60th annual Beanpot from TD Garden.
Matt Nieto also scored for the Terriers, who advance to the final for the eighth time in the last 10 years.
Alex Killorn notched the lone goal for the Crimson, who take on the loser of BC-Northeastern in the consolation game. Starter Steve Michalek was pulled after allowing three goals on 17 shots. Raphael Girard stopped all eight shots he faced the rest of the way.
Nieto gave the Terriers a lead at 8:14 of the first period on wraparound shot that deflected off a Harvard defenseman's skate before settling into the net.
Megan doubled the BU edge on a power-play goal 7 1/2 minutes into the second as he tapped in a Sean Escobedo pass at the right post. He struck again inside of six minutes left in the period by taking a puck off the boards, cutting to the net and slipping a backhander home to make it 3-0.
Killorn clicked on the advantage with 4:33 remaining in the middle stanza but Millan shut the door with 10 stops in the third.