The forward hopped off the bench and received a pass from Blake Lizotte before beating Tristan Jarry glove side on a breakaway. The goal came after Los Angeles let a 3-1 lead slip in the third.
"Bench was positive," Moore said. "Keep going. Keep doing our thing. Don't change anything. I thought that would lead to success."
Cal Petersen made 23 saves, and Anze Kopitar had two assists for the Kings (23-16-7), who are 3-0-2 on a six-game road trip.
Sidney Crosby scored his 498th NHL goal, and Bryan Rust scored twice for the Penguins (27-11-7), who are 0-1-2 since winning six straight. Jarry made 34 saves.
"We've had moments where we've been better, but it hasn't been consistent," Pittsburgh coach Mike Sullivan said. "That's the game that we have to bring is a consistent game. Right now, it's just not as consistent. … Part of it is on the execution side. When the play is there to be made, we have to make them. When they're not, we can't be stubborn.
"We have to be willing to put pucks deep and create offense different ways. So those recognition skills on when to make simple plays are really important. But also, the execution side is really important."