Evgeni Malkin scored, and Tristan Jarry allowed five goals on 19 shots before being pulled at 13:37 of the second period for the Penguins (31-14-8), who have been outscored 14-5 during the losing streak. Casey DeSmith made 16 saves.
"I just think, to a certain extent, the last few games, we've beaten ourselves in a lot of ways, a lot of different ways," Pittsburgh coach Mike Sullivan said. "I don't think it's from a lack of effort. In certain areas, there's lapses in the game where we're just not diligent.
"I was really looking forward to tonight's game because I was really excited about watching our team. Obviously, we didn't get the start that we wanted."
New Jersey scored on three of its first seven shots.
Bratt put the Devils ahead 1-0 at 1:16 of the first period. Hischier chipped the puck between Penguins defenseman Marcus Pettersson's legs for Bratt to tap in from the left post.
Bratt made it 2-0 at 5:47 on a wrist shot from the right face-off circle. The forward missed two games with an upper-body injury.
"We were all worried about an eight-day break," New Jersey coach Lindy Ruff said. "How you manage it, how hard you practice, the time off. I thought, looking back now, we did the right thing. Went hard for a couple days. We gave them their rest period, gave them another day.
"In [Bratt's] case, with not playing and then taking some extra days, although I think he skated a couple of those days, I felt his game was on cue."
Yegor Sharangovich extended the lead to 3-0 at 6:44 from just outside the crease.
Dawson Mercer pushed the lead to 4-0 at 9:24 of the second period on New Jersey's first shot of the period. Hughes forced Pettersson into a turnover behind the net and passed to Mercer out front for a wrist shot.
Malkin cut it to 4-1 on the power play at 11:13. He kicked a pass from Sidney Crosby to his stick for a snap shot.
"It starts with a good start, that would go a long way," Crosby said. "We've been chasing games here the last few. It hasn't turned out great for us. So I think if we just start there and try to put a few periods together, we just have to be better. We're not playing the way we're capable of."