Buchholz fanned three and allowed just two hits over his start, winning his second of the spring.
Brandon Snyder, Sean Coyle and Corey Brown each drove in a run for the victorious Red Sox.
Kevin Pillar knocked in Jonathan Diaz for the Blue Jays' lone offense.
Drew Hutchison worked 4 2/3 frames, taking the hard-luck loss after allowing one run on four hits. He fanned seven and did not issue a walk.