Victorino's career-high RBI performance began with a two-run shot in the third that put Boston ahead to stay and continued with a three-run homer in the fifth.
He capped his big night with a two-run double in the seventh as the American League East-leading Red Sox posted a one-sided win to begin a key three-game series.
Mike Napoli added a solo homer for Boston.
Doubront (10-6) gave up two runs on four hits over 6 2/3 innings, walking one and striking out seven.
Orioles starter Wei-Yin Chen (7-7) was roughed up for eight runs on eight hits in just 3 2/3 innings.
Brian Roberts and Manny Machado each drove in a run for Baltimore, which fell 3 1/2 games out of an AL wild card slot.