Gerhart was signed by the Cleveland Browns after going undrafted in the 2012 NFL Draft before signing with the Packers on January 8, 2013. He was released from the Packers on August 31, 2013. He was signed to the Carolina Panthers' practice squad for the beginning of the 2013 season before shortly being released. Gerhart was signed to the Green Bay Packers' practice squad on October 10, 2013. He was later signed to the active roster before Week 1 of the 2014 season. On January 5, 2016, Gerhart signed a reserve/futures contract with the Cleveland Browns. On September 3, 2016, he was released by the Browns.