It was the season opener for both teams.
Hendrix Lapierre had a goal and an assist, and Ville Koivunen and Evgeni Malkin also scored for the Penguins. Kaedan Korczak and Samuel Girard each had two assists, and Arturs Silovs made 19 saves for his third shutout in the NHL.
Dan Vladar made 31 saves for the Flyers, who eliminated Pittsburgh in six games in the Eastern Conference First Round last season.
Robertson gave the Penguins a 1-0 lead at 7:26 of the first period. Kris Letang sent a pass from the top of the right face-off circle to Robertson, who redirected it past Vladar's glove from the right of the net.
It was Robertson's first game with the Penguins after he was acquired from the Toronto Maple Leafs for a fourth-round pick in the 2028 NHL Draft on July 1.
Koivunen made it 2-0 at 15:44, slipping behind the defense and sliding a backhander through Vladar's pads on a breakaway.
Malkin extended the lead to 3-0 with a power-play goal at 5:03 of the second period, finishing a give-and-go with Lapierre with a one-timer from the left circle.
Lapierre pushed it to 4-0 at 7:26 on a 2-on-1 rush with a wrist shot from the left circle that beat Vladar to the blocker side.
Lapierre made his Penguins debut after being acquired from the Washington Capitals on June 25 for a third-round pick in the 2027 NHL Draft and fifth-round pick in the 2028 NHL Draft.
Hallander made it 5-0 at 10:23, knocking a loose puck past a sprawling Vladar from the front of the net.
Robertson scored the first short-handed goal of his career to put the Penguins up 6-0 at 11:52 of the third period. His shot rebounded off the end boards and was kicked into the net by Vladar.
Egor Chinakhov tipped a point shot from Erik Karlsson while on the power play at 16:37 for the 7-0 final.
