Allen ran for 195 yards and three touchdowns and Georgia Tech posted its best rushing total in an Atlantic Coast Conference game to beat Virginia 33-21 on Saturday.
Allen had touchdown runs of 6, 18 and 8 yards in the second half. The Yellow Jackets had 477 yards rushing, the fifth-best total in school history and their top total in an ACC game.
The big game was overdue for Allen, a senior who has taken over for Jonathan Dwyer at the Yellow Jackets' featured B-back position.
"Man, I didn't know what to do," Allen said of long-awaited first touchdown. "It felt good to score my first touchdown -- and my second and third."
Georgia Tech (4-2, 3-1) has back-to-back wins for the first time this season.
"Good win to build on," said coach Paul Johnson.
Quarterback Joshua Nesbitt added 21 carries for 109 yards and a touchdown. He overcame an interception and a lost fumble.
Nesbitt had a 31-yard pass to Stephen Hill on the first play of the game, setting the stage for a day of big gains for the Yellow Jackets.
Allen had long runs of 44 and 20 yards. Nesbitt had a 67-yard run, and Roddy Jones had a 31-yard run.
"It seemed like we'd stop them and we'd stop them, then all of a sudden they'd break one," said Virginia coach Mike London. "You can't do that against a team that's No. 1 in the conference in rushing and sixth in the country. They're very good at what they do, and we had no margin for error."
The Yellow Jackets' previous best rushing total in an ACC game was 472 yards against Miami in 2008.
Virginia (2-3, 0-2) suffered its second consecutive ACC loss.
London took over for Al Groh, who was fired last year after nine seasons as Virginia's coach. He was hired by Johnson to head Georgia Tech's defense.
Groh's defense held the Cavaliers to only 3 of 12 third-down conversions.
Virginia quarterback Marc Verica completed 18 of 31 passes for 239 yards and no touchdowns.
Verica was sacked four times as the Cavaliers struggled after a week of emphasizing third-down production.
"We've got to protect the quarterback better," London said. "That's the commonality. Teams are going to come at you on third down, and you have to be prepared and ready to block what they throw at you. You've got to get it off and run the right routes. We need to address that once again this week."
Allen needed another 5 yards to become Georgia Tech's first player to rush for 200 yards since Roddy Jones had 214 in a win over Georgia on Nov. 29, 2008.
"I thought he played really good," Johnson said. "He ran through a lot of tackles."
Allen's previous high was 127 yards rushing against Clemson last season.