Fiala scored into an open net off a no-look pass from Phillip Danault to give the Kings their third straight win.
You are reading: Kevin Fiala beats OT buzzer to give Kings win over Blackhawks
Danault had a goal and an assist for Los Angeles, which has won four straight on home ice.
Taylor Raddysh scored on the power play and Petr Mrazek stopped 32 shots in his first start since injuring his groin Oct. 21, but the Blackhawks lost for the sixth time in seven games.
Danault tied it 1-all early in the second period on a one-timer set up by Viktor Arvidsson shortly after a Kings power play expired. Danault had gone eight games without a goal before netting his fifth of the season.
Los Angeles appeared to take the lead when Anze Kopitar put the puck in the net at 6:09 of the second, but the goal was waived off because Fiala was called for hooking.
Chicago struck first on a power play late in the opening period. Raddysh positioned himself right in the slot to bury a one-timer from Jonathan Toews for his fourth goal.
It was the second power-play goal in 10 opportunities over the past five games for the struggling Blackhawks.
Chicago ended the game 1 for 4 on the power play. Los Angeles was 0 for 4.