Dwayne Roloson, who could be moved by Wednesday's trade deadline, made 41 saves in his first win since Jan. 21. Roloson also stopped 20 first-period shots to keep his team in contention.
"That first period, Rollie came up huge for us to keep it close and allow us to get our legs underneath us," Islanders coach Scott Gordon said.
Comeau scored twice in the second period, including an insurance goal with 17 seconds left that made it 5-2 and marked the Islanders' first three-goal game since Jeff Tambellini accomplished the feat on Oct. 31.
"He had a great shot before he changed sticks," Gordon said. "It's [about] getting him to understand to use his shot when he has the opportunity instead of looking for the pass."
Kane, who helped the Americans win a silver medal, had his 19th multipoint game this season. Chicago wasted a chance to tie San Jose (89 points) for the league's best record.
Blackhawks starting goalie Antti Niemi allowed three goals on just 12 shots before getting pulled. Chicago lost its fifth straight against the Islanders and hasn't beaten them since Dec. 23, 2002, at the Nassau Coliseum.
"They have some young players over there who I think will be pretty good in the future and they showed it tonight," Kane said. "It's not our best performance but we can regroup here."
Comeau never scored two goals through his first 151 NHL games, but notched his second straight multigoal game. The 24-year-old Comeau scored twice against Ottawa on Feb. 14 and has six goals in his past three games.
"I'm just shooting the puck more and guys are making good plays," Comeau said. "They seem to be going in for me."
Chicago initially looked rejuvenated off the two-week Olympic break, firing 22 shots in the first period to take a 2-1 lead.
Campbell opened the scoring 10:44 in for his 17th goal. Roloson knocked down Kane's shot from the right circle before Campbell slammed home the rebound at the right post.
Despite the shot disparity, Comeau tied it after stopping a sideboards-bound clearing pass and beating Niemi glove-side 1:32 later.
But Chicago quickly regained momentum off Richard Park's slashing penalty. Kane's wraparound rebound goal off Duncan Keith's off-target shot came just 63 seconds after Comeau's tally. The Blackhawks fell two short of tying their season high of 24 shots in a period, accomplished in the season opener against Florida.
"They played with a lot of pace in the first period and we were a step behind in every area," Gordon said. "We'd get the puck and we were too slow to move it."
Momentum shifted coming out of first intermission when Comeau and Sim scored 25 seconds apart to force Niemi to the bench 2:52 into the second.
"When we got in trouble, we were caught flat-footed and we let the other team dictate the play," Keith said.
Comeau's drive from the left circle hit just under the crossbar and Sim followed with a point-blank rebound goal a half-minute later, prompting Chicago coach Joel Quenneville to insert Cristobal Huet.
"Our guys did a great job creating the turnovers and not allowing them to get through the neutral zone," Roloson said.
Islanders C Josh Bailey (upper body) returned to the lineup after missing the last six games. ... Islanders D Jack Hillen returned from a nine-game absence after breaking his jaw on Jan. 26 against Washington. ... New York recalled D Dustin Kohn following the Sutton trade and he had an assist. ... Chicago's previous road loss came Jan. 30 in Carolina. ... The Blackhawks have allowed 16 goals the last four games but are 3-1 in that stretch.