Sam Bennett scored twice for the Panthers, who dropped their second straight game after a franchise-record nine-game winning streak. Sam Reinhart and Carter Verhaeghe also scored. Former Duck Anthony Stolarz had 21 saves.
Ross Johnston nearly gave Anaheim an early advantage with a breakaway against Stolarz, but the former Duck answered with a blocker save to briefly keep the contest scoreless.
Instead, a few minutes later, it would be Bennett putting the home side ahead first on a tough bounce for the Ducks, as Killorn intercepted a cross-ice pass with his skate but saw the carrom go right to Bennett, who beat Gibson glove-side from the slot.
Florida remains the only team in the NHL this season without a regulation loss when scoring the game's first goal (17-0-3).
Bennett's goal marked Florida's ninth straight game scoring on the power play.
Reinhart doubled the lead for Florida a few minutes later as the finisher on a shorthanded 2-on-1 rush with Mikkola after an Anaheim turnover.
Reinhart has scored in seven straight games, matching Hockey Hall of Famer Pavel Bure for the longest streak in franchise history. Now in his third year with Florida, Reinhart ranks second among NHL leaders in goals this season (32), trailing only Toronto's Auston Matthews, and is one goal shy of his career-high (33) with 39 games still to play.
The goal also pulled Reinhart within one point of 500 for his NHL career.
Just as it appeared the Panthers would take that 2-0 lead back to the locker room, Killorn put the Ducks on the board with a breakaway goal in the very final moments of the frame. After a faceoff in the Anaheim zone, Henrique poked the puck away from defenseman Oliver Ekman-Larsson at the blue line, allowing Killorn to skate in alone for a quick move to the forehand past an outstretched Stolarz.