Evan Rodrigues and Nathan MacKinnon scored, and Alexandar Georgiev made 26 saves for the Avalanche (35-22-6), who have lost four of five (1-3-1).
Colorado remained in third place in the Central Division, five points behind the Minnesota Wild, who have two games in hand, for second. The Avalanche are just one point ahead of the Winnipeg Jets, who hold the second wild card into the Stanley Cup Playoffs from the Western Conference.
"I think that we have another level yet against these good teams that we have to get to," Colorado coach Jared Bednar said. "With the passion of our game, the intensity of our game, the competitiveness in those important areas, net front, we weren't good enough. We played pretty smart. The scoring chances against weren't real high. I just didn't like a couple of the ones we gave up. They just seemed too easy."
Kempe made it 1-0 at 8:37 of the first period when he finished a 2-on-1, circle-to-circle pass from Kopitar.
"He's been hot for the majority of the season," Kopitar said. "He's [hit] a couple bumps in the road, but always a safe bet to give him the puck."
Gabriel Vilardi extended the lead to 2-0 at 17:10 when he sniped a shot from the left circle short side over the shoulder of Georgiev.
Rodrigues cut it to 2-1 when he deflected a point shot from Samuel Girard at 14:59 of the second period.
"We had a handful of shifts like that," Bednar said. "But that particular shift, we extended some good o-zone time. We were shooting. We had good intent to get to the net, and we end up getting a deflection out of it."
Kempe made it 3-1 just 24 seconds into the third period when his backhand shot from just above the crease caromed off Georgiev's stick and fluttered into the net.
"That's huge because you're back on your heels a little bit. They've got some energy, a clean sheet, their building, their fans behind them," McLellan said of the fast goal. "So, to quiet things down a little bit was a benefit to us quickly in that third."