The Flashes junior made the announcement on social media Tuesday.
As a sophomore last season, Gradishar led the Flashes with a .629 batting average with 18 home runs and 59 runs scored. She also recorded 17 wins as a starting pitcher with 249 strikeouts and a 0.94 ERA.
Gradishar helped lead Champion to 25 wins and the Division III District Championship.
The Penn State softball team was 31-16 last season and 11-11 in the Big Ten. Gradishar chose the Nittany Lions over Ohio State and Michigan State.