Lewis' had a 7-yard touchdown run in the first quarter and capped his day with an 85-yard touchdown run in the fourth quarter.
Stull was 21-for-30 passing for 172 yards. His longest TD pass was a 23-yarder to Dickerson and Stull scored on a 3-yard rollout, which put Pitt (2-0) up 34-14 before halftime.
Dickerson finished with eight receptions for 71 yards and the three TDs.
Buffalo (1-1), playing its first home game since winning the Mid-American Conference title last season, got four touchdown passes from Zach Maynard, who threw for 400 yards in his home debut as a starter.
But four Buffalo turnovers led to 27 Pittsburgh points. Mario Henry fumbled twice and Maynard lost the ball on a pitch, which Pittsburgh's Greg Williams returned 50 yards for a score.
Down 40-27 in the fourth, Maynard had the Bulls driving in hopes of a comeback. But on the Pitt 14-yard line on second-and-4, the Panthers' Adam Gunn sacked Maynard for a 6-yard loss and his next two passes were incomplete.
Maynard also was intercepted late in the fourth quarter by Elijah Fields, who returned the ball to the Buffalo 2. Ray Graham scored on a 2-yard run for Pitt's final points.
Though Buffalo had 500 yards of total offense, only 67 came on the ground, while the Panthers rushed for 209 yards. Pittsburgh was a perfect 5-for-5 in the red zone, but also had 11 penalties for 119 yards.