Recchi's power-play tally was the second of four unanswered Bruins goals in the second period. He added another marker late in the game for Boston, which cut the Canucks' lead in the Finals to 2-1.
Andrew Ference, Brad Marchand and David Krejci also scored in middle frame, as the Bruins responded to a vicious hit laid on playoff hero Nathan Horton by Vancouver's Aaron Rome late in the first period.
Rome was given a game misconduct on the play and Horton was taken off the ice on a stretcher. He was transported to a Boston hospital where Bruins team officials said he was moving all of his extremities.
Daniel Paille, Chris Kelly and Michael Ryder scored for Boston during a fight-filled third period during which nine misconduct penalties handed out.
Thomas, who has played every minute in net during Boston's 21 playoff games, stopped 40-of-41 shots, including 16 in the second period.
Jannik Hansen notched Vancouver's only goal and Robert Luongo made 30 saves for the Canucks, who will attempt to rebound in Wednesday's Game 4.