Beaver was named the outstanding player in Division III football in 2007. As the running back for the UW–Whitewater Warhawks he set conference rushing records for the Warhawks and the WIAC. His contributions to the Warhawks led them to their third consecutive appearance in the Amos Alonzo Stagg Bowl game, in Salem, VA. During the Championship Game, Beaver ran for 253 yards and one touchdown, topping his single season team record from 2005, and helping the Warhawks win 31-21 over Mount Union.
Beaver was named 2007 winner of the Gagliardi Trophy, named for John Gagliardi, for the outstanding player in the 2007 season of NCAADivision III Football.
According to NCAA football statistics, Justin is 11th all-time in NCAA rushing, only a few yards behind Ron Dayne for 10th all-time.
After not being selected in the 2008 NFL Draft or offered a contract as an undrafted free agent by any NFL team, Beaver was invited to attend the 2008 rookie mini camp. After the camp was over, the Packers informed his representatives that they will not be signing him to a contract.