McDavid was out the previous six games after sustaining the injury against the Nashville Predators on Feb. 8.
Leon Draisaitl had a power-play goal for the Oilers (33-22-7), who moved into second place in the Pacific Division, one point ahead of the Vancouver Canucks. Mike Smith made 21 saves.
"I felt a little awkward at first but settled in as game went on," McDavid said. "I think timing is the main thing. The game can feel a little bit weird when you've been sitting out for a bit."
WATCH: [All Oilers vs. Kings highlights]
Anze Kopitar scored a power-play goal, and Adrian Kempe had two assists for the Kings (22-35-6). Cal Petersen made 27 saves.
"I thought we had some good moments," Los Angeles coach Todd McLellan said. "The negatives were the outnumbered rushes that we gave up to their two top players (McDavid and Draisaitl). We really tried to focus on that before the game."
McDavid gave the Oilers a 3-0 lead at 16:14 of the second period, keeping the puck on a 2-on-1 break and putting a backhand shot past Petersen.
"We had two or three 2-on-1s that kind of worked out the exact same way right before that, so I thought [Kings defenseman Drew Doughty] might go and stand with [Oilers forward] Sam [Gagner], and it just gave me a chance to make a move," McDavid said.
McDavid has 20 points (nine goals, 11 assists) in his past 13 games. He had three goals and six assists in four games against the Kings, including two of his 23 multipoint games this season.
"Of course it's great having him back," Oilers center Ryan Nugent-Hopkins said. "You see the plays he makes and he's just so dangerous every time he touches the puck, and every team knows that. It's no secret, [yet] he still goes in and does it every night. For him to play like that in his first game back, it's more than impressive."