The Knights (10-3), who began the season 0-3, will go for their second district championship in the last three years against No. 4 Neshaminy at 7 p.m. next Friday at Souderton.
That title shot seemed tenuous, at best, when Perkiomen Valley (11-2) led by 19-13 after two quarters.
Stewart, who took the first play from scrimmage 82 yards for a touchdown, had 128 yards and three touchdowns on five carries in the first half and had 110 yards passing.
In the second half, North Penn held him to 18 yards on six rushes and 4-for-11 passing.
"That quarterback's a great player, and we just knew we had to keep it out of his hands," Shearer said. "That was as dominating a second half as you're going to see from us."
Nyfease West carried the ball 23 times for 191 yards and two touchdowns. Luke Berry, the body blow to complement West's jab, had 154 yards and two TDs on 25 rushes.
"They might have even known the plays we were running," Shearer said. "But they couldn't take [Berry] down with one tackler."
The most crushing blow came on the final two plays of the third quarter.
Perkiomen Valley nearly scored on a trick play, a double-reverse wideout pass that Kris Akins broke up in the corner of the end zone.
On the next play, Shearer hit Nick Wright, who appeared to be stopped after about a 40-yard gain. Instead, Wright bounced off several tacklers and dragged the rest, going all the way for a 68-yard score.
Like the Knights season, he had plenty of life left.
Perkiomen Valley 6 13 0 0 – 19
North Penn 7 6 20 7 – 40
PV: Rasaan Stewart 82 run (run failed)
NP: Nyfease West 68 run (Matt Ammendola kick)
NP: FG Ammendola 36
PV: Stewart 5 run (Matt Genuardi kick)
PV: Stewart 33 run (kick blocked)
NP: FG Ammendola 20
NP: West 12 run (run failed)
NP: Luke Berry 2 run (Ammendola kick)
NP: Nick Wright 68 pass from Austin Shearer (Ammendola kick)
NP: Berry 1 run (Ammendola kick)