Horwat picked up a win and a save in two relief appearances against the Terrapins to help Penn State secure a spot in the Big Ten Tournament.
The Nittany Lions will take on the Illini at 7 p.m. on Tuesday in Omaha, Nebraska.
A three-run home run and a grand slam secured the win for Penn State.
The Nittany Lions missed last year's tournament.
The Nittany Lions gave up three runs in the sixth inning.
The Nittany Lions allowed eight runs in the seventh inning.