The win was No. 253 for Sullivan, passing Dan Bylsma. Sullivan is 253-131-44 in seven seasons with Pittsburgh, which includes two Stanley Cup championships (2016, 2017).
"I just give our guys credit," Sullivan said. "They're playing hard. I think they're playing, collectively, as a group. They're trusting one another out there. The players, they're playing the game hard. They're executing."
Drew O'Connor scored his first NHL goal and had an assist, Danton Heinen scored in a third straight game and Tristan Jarry made 18 saves for the Penguins, who began an eight-game homestand. They started their season winning at the Tampa Bay Lightning 6-2 on Tuesday and losing 5-4 in overtime at the Florida Panthers on Thursday.
Marc-Andre Fleury was pulled after allowing four goals on 10 shots in the first 11:25 of the first period for the Blackhawks (0-2-1). Kevin Lankinen made 15 saves in relief.
Fleury had not faced the Penguins, his first NHL team, since Jan. 7, 2020, with the Vegas Golden Knights.
"Obviously, feel bad tonight leaving [Fleury] out to dry," Chicago forward Patrick Kane said. "Especially him coming back to Pittsburgh, to perform like that in front of him in the first period is unacceptable. But we'll find a way to turn it around. I have a lot of confidence in the team we have."
Teddy Blueger scored on the first shot of the game, putting the Penguins ahead 1-0. He attempted a backhand pass to Zach Aston-Reese that went through Fleury's five-hole 15 seconds into the first.
O'Connor made it 2-0 at 5:33 of the first. Fleury went behind the net before Dominik Simon forced an errant pass O'Connor intercepted and wrapped around the left post.
"I haven't checked my phone yet," O'Connor said. "I'll probably hear from some people. Talk to my parents and family, girlfriend and friends. I'm sure I'll be hearing from a lot of people."