Hamler is ranked No. 10 among wide receiver prospects for the 2020 NFL draft by ESPN's Mel Kiper.
He wrote in a statement posted to Twitter that he has "decided to pursue my lifelong dream of playing in the NFL."
Hamler caught 56 passes for 904 yards and eight touchdowns this season for the Nittany Lions.
He ranks No. 10 on Penn State's all-time kickoff return list with a 25.2-yard average and in 2018 broke Saquon Barkley's all-purpose yards record when he finished with 1,417 yards. Barkley had set the school mark in 2015 when he finished with 1,237 all-purpose yards.