Colorado went ahead 2-1 at 13:57 when Colin Wilson scored on a 5-on-3 power play off a pass from Alex Kerfoot, who was at the base of the left face-off circle.
"It's a 5-on-3 so there's a lot of room out there," said Kerfoot, who had two assists. "We had a couple really good looks before that. He was open in front of the net and I tried to just feather it in there and he made a good play to finish it."
Sven Andrighetto scored to make it 3-1 at 1:26 of the third period on a deflection of Erik Johnson's shot.
"A couple quick shots from Nemeth and Johnson, and then guys were just getting in the goalie's eyes and trying to get tips, screens, rebounds," Avalanche coach Jared Bednar said. "It gets us two goals and we get a 5-on-3 goal as well, so it's a recipe for success and we got to keep fighting to get there. That's where most goals are scored, from the front of the net, and we got a few like that today."
The Blackhawks pulled to within 3-2 at 12:04 when Gustafsson scored from inside the blue line.
Derick Brassard scored an empty-net goal with 2:20 remaining to give Colorado a 4-2 lead.