Cam Atkinson had a goal and an assist, and Matt Duchene and Oliver Bjorkstrand tallied for the Blue Jackets, who have won 10 of their last 11 games, including seven of eight to close the regular season and earn the second wild-card spot in the Eastern Conference.
Bobrovsky stopped 16 shots in the third period, as Tampa Bay tried to rally from a 2-0 deficit but couldn't do so in front of a raucous crowd at Nationwide Arena. The Blue Jackets can close out the series against club in Game 4 in Columbus on Tuesday.
Ondrej Palat scored a goal, and Andrei Vasilevskiy made 27 saves for the Presidents' Trophy-winning Lightning, who tied an NHL single-season record with 62 regular-season wins and dropped their third straight game for the first time this season.
Jordan Eberle scored his third goal in as many games as New York took a commanding lead in its first-round playoff series with host Pittsburgh.
Brock Nelson, Leo Komarov and Anders Lee also scored for the Islanders, who took a 3-0 lead in the best-of-seven series, with Game 4 set for Tuesday in Pittsburgh. New York spotted Pittsburgh a 1-0 lead before netting four unanswered goals.
The Penguins, who won the Stanley Cup in 2016 and 2017, continued to be thwarted by the Islanders' stifling pressure and the play of goaltender Robin Lehner, who made 25 saves Sunday.
Second-period goals four minutes apart by Kevin Hayes, Patrik Laine and Kyle Connor, who scored two goals in the game, sent Winnipeg off and running to a road victory over St. Louis.
The Jets, who lost the first two games of the series on their home ice, pulled to within 2-1 in the best-of-seven Stanley Cup playoffs series. Game 4 will be Tuesday in St. Louis.
Brandon Tanev and Dustin Byfuglien also scored for the Jets, who got 26 saves from Connor Hellebuyck. David Perron, Vladimir Tarasenko and Alex Steen scored for the Blues, who got 23 saves from Jordan Binnington.