Jacob Markstrom, starting on consecutive nights, made 20 saves for his fifth straight win. He got some help from Horvat and new wings Antoine Roussel and Loui Eriksson, who were moved up the lineup to match up against Oilers center Connor McDavid.
McDavid extended his point streak to nine games with an assist on Chiasson's goal but finished with one shot on goal in 23:38 of ice time. The Oilers were held to fewer than four goals for the second time in the past six games
"Anytime you get to go up against the best player in the world you've got to raise your game, you've got to raise your level," Horvat said. "I thought we did a great job."
Ryan Nugent-Hopkins scored in the second period and Mikko Koskinen made 26 saves for the Oilers (18-13-3), who lost in regulation for the first time in seven games (5-1-1).
Edmonton is 9-3-2 since coach Ken Hitchcock replaced Todd McLellan on Nov. 20.
Hitchcock wasn't happy with how the Canucks played McDavid.
"We're a league that's supposed to showcase our top players and you don't want to give him all the freedom," Hitchcock said. "He's not allowed to play give and go. It's give and hold.
"We're going to have to figure out how to fight through it."
Nugent-Hopkins gave the Oilers a 1-0 lead at 1:40 into the second period, taking a blind backhand pass from Jujhar Khaira through the slot and beating Markstrom.
Edler tied it 1-1 on a power-play one-timer from the top of the left face-off circle at 11:49 of the second period, and Boeser made it 2-1 with another power-play goal at 14:46. He scored off the rush from just inside the top of the right face-off circle with a wrist shot off Koskinen's glove.
"We showed we can out-play them five-on-five, but unfortunately we just took too many penalties and they started to get momentum and we just couldn't claw our way back," Nugent-Hopkins said.
Pettersson made it 3-1 at 3:04 of the third period with a wrist shot over Koskinen's glove from the right face-off dot for his 17th goal of the season, most among NHL rookies.
"I was trying to fake out the goalie by looking for a tip-in pass but try to go short-side high and it went home," said Pettersson, who has four goals and nine assists during a seven-game point streak.
Chiasson got open in the slot and converted a passout from McDavid to make it 3-2. McDavid has six goals and 10 assists during his nine-game point streak.
