The 6-foot, 185-pounder, who took over at QB after the graduation of Billy Fleming, scored on runs of 4, 79, and 45 yards to help the Golden Hawks (2-0) overcome a 21-7 deficit.
"He's been great for us," senior two-way lineman Andrew Cohen said. "If we don't have him, our offense wouldn't be as productive as it is. It all revolves around him."
C.R. South's wishbone attack netted 320 rushing yards. Junior fullback P.J. Steinmetz chipped in 27 yards on six attempts.
"Our offensive line does a great job of creating gaps," Donnelly said. "We rely on them in a big way. The guys up front came though for us against a very physical Judge team."
The difference, late in the third quarter, was Donnelly's 45-yard touchdown scamper and an extra-point boot by Ben Solis.
Midway through the fourth quarter, Judge's Rob Daniels connected with John Landis for a 32-yard score that made it 35-34. On a two-point conversion try, Anthony Walker caught and then dropped, the officials ruled, a right-side toss from Tim Mills.
Donnelly, of Collegeville, is a Division I prospect in baseball. Over the summer, the centerfielder and pitcher played for the All-Star Baseball Academy. He thought seriously about continuing with the squad in the fall months.
"I sat down with my parents about 15 to 20 times to discuss what to do," he said. "I think they wanted me to play baseball, mostly because that's the sport I'll be playing in college."
Last season, as a halfback, Donnelly rushed 86 times for 561 yards and two TDs as the Golden Hawks went 11-2 and advanced to the PIAA District 1 Class AAAA semifinals.
"I've been waiting for two years for the opportunity to play quarterback," he said. "You can be very successful running this offense if you do what you're supposed to do and stay within yourself."
In the first quarter, thanks to a 41-yard pass from Ron Daniels to Raul Quinones and Matt Smalley's 76-yard jaunt, Judge (1-1) was in front, 14-0.