Jake Muzzin, Marian Gaborik and captain Dustin Brown scored in a dominant first period, helping Los Angeles beat Chicago 5-2 to take a 3-1 series lead.
Muzzin and Drew Doughty each had a goal and an assist, and Jonathan Quick made 22 saves as the Kings moved to the brink of their second trip to the Stanley Cup Final in three seasons with their third straight win over the Blackhawks.
"To come into every game with that confidence, to have that mojo that you can win every game, that's the difference,'' Gaborik said. "It's great to come to a team like this and be part of a winning culture.''
Tanner Pearson added an empty-net goal for the Kings, who have been to the NHL finals just twice, winning their only title in 2012.
One year after Los Angeles lost the conference finals in five games to Chicago, the Kings have their own chance to close it out in five.
Two days after the Kings gritted out a 4-3 victory over Chicago in Game 3, they won again at Staples Center by scoring three goals on their first six shots of Game 4, capping an incredible three-game offensive performance by the lowest-scoring NHL team to make the postseason.
Unbelievable Kings' comeback
After trailing 2-0 late in the second period of Game 2, Los Angeles scored 13 goals in less than 100 minutes.
Muzzin scored on a power play. Gaborik added his 10th goal of the postseason off Duncan Keith's turnover.
Brown banged a puck into an open net for another power-play goal, his first score since Game 7 of the first round against San Jose.
Brandon Saad and Bryan Bickell scored and Corey Crawford stopped 16 shots for the Blackhawks, who didn't get rolling until they trailed 4-0 late in the second period.
The Blackhawks escaped a 3-1 hole in the second round against Detroit last season, but that's the only time in franchise history Chicago has rallied from that deficit - and the Kings are an entirely different postseason challenge.
The Eastern Conference final is similarly poised, with the New York Rangers taking a 3-1 lead to Montreal.