Stephen Weiss had given the Panthers the lead with a tally in the top of the third round, but Patrice Bergeron -- who notched both of Boston's regulation goals -- forced a fourth frame when he got one past Scott Clemmensen.
Florida's Mikael Samuelsson then missed the net and Krejci iced the victory with a shot between Clemmensen's pads, handing the Northeast Division-leading Bruins their fifth win in eight games.
Tuukka Rask turned aside 38-of-40 shots for Boston.
Jason Garrison and Shawn Matthias scored for the Panthers, who lost for the fourth time in five games but pulled into a tie with Washington atop the Southeast Division with the single point.
Clemmensen finished with 33 saves.
Attkisson leaves CBS News, reportedly over network's 'liberal bias'
Astronomers offer more expansive view of universe