Matt Fraser scored a pair of goals and the Oilers dealt a blow to the postseason hopes of the defending Stanley Cup champions with a 4-2 victory on Tuesday.
Jake Muzzin and Drew Doughty scored for the Kings (39-26-15), who have lost two straight at a time when they can't afford to let any points escape.
"We just didn't have enough energy, enough jump," Kings forward Anze Kopitar said. "We didn't play our style of game. I don't know what the reason was. It just wasn't good enough. That's the bottom line."
Los Angeles trails Winnipeg by three points and the Calgary Flames by two points with only two games remaining for all three teams in the hunt for the final two playoff spots in the Western Conference.
"We just have to win our next game and go from there," Kings winger Marian Gaborik said. "We are obviously disappointed to be in this position, but we have to go to Calgary (on Thursday) and win. That's all there is to it."
Added L.A. coach Darryl Sutter: "We have to win. ... We've been saying that for a while."
Benoit Pouliot and Tyler Pitlick also scored for the Oilers (24-43-13), who snapped a three-game skid and relished the role of throwing a wrench into the Kings' playoff plans.
"We came into this game wanting to play the spoiler," Fraser said. "We wanted to play our own game and have a little redemption for what happened (an 8-2 loss) in their rink last week."
Added Taylor Hall: "It's fun to knock off a team that's had so much success lately. I'm sure other teams are pretty happy."
The Kings loss clinched a playoff spot for the Vancouver Canucks.
After a scoreless first, the Oilers broke the tie 2:34 into the second period as Fraser tipped Martin Marincin's shot and then swept his own rebound into an open net behind L.A. goalie Martin Jones.
The Kings tied it up on the power play at 5:44 of the second as a Kopitar shot came off the boards right to Muzzin at the side of the net for an easy goal on Edmonton starter Richard Bachman. Doughty picked up his 200th assist on the play.
Pouliot stole a puck from Trevor Lewis and went in alone before beating Jones stick-side to help the Oilers regain the lead at 10:09 of the second.
Edmonton went up 3-1 at 5:31 of the third as Pitlick took a bounce off the boards in front and picked the top corner in his return to the lineup after missing 41 games with a spleen injury.
The Kings closed back within one at 9:38 of the third as Doughty took a power-play shot from center ice and it trickled through Bachman.
Fraser put the game away for the Oilers with an empty-net goal.
Both teams return to the ice on Thursday as the Kings play a crucial game in Calgary, while the Oilers play their final home game against San Jose.
Notes: Edmonton came into the game with a record of just 1-8-1 in their past 10 games against the Kings, including a humbling 8-2 road loss last Thursday. ... Bachman returned from a personal leave. ... Jones was a surprise start for the Kings, but had recorded shutouts in both of his previous appearances against the Oilers.