Elias Pettersson had two goals and an assist, and Brock Boeser had a goal and three assists for the Canucks (21-27-4), who responded after a 4-3 loss at the New York Rangers on Wednesday. Collin Delia made 24 saves.
"We were doing [well]," Petersson said. "Our pace was there. I think everyone felt we [had] jump, that we [could] get some goals today. It felt good to win."
Mathew Barzal had a goal and two assists, and Noah Dobson had a goal and an assist for the Islanders (27-23-5), who had won four in a row and led 4-2 in the second period. Ilya Sorokin, who had a shutout in each of his previous two starts, allowed six goals in 34 shots.
Horvat, who had 31 goals for Vancouver this season, scored in his second straight game for New York. He was Canucks captain from the start of the 2019-20 season until the trade and had 420 points (201 goals, 219 assists) in 621 games for them after being a first-round pick (No. 9) at the 2013 NHL Draft.
"If you were going to write it up any way … obviously, I would have liked to get the win," Horvat said. "I'm glad both of us got on the board at least against our former teams, but it stings a little bit that we didn't get that win."