The How I Met Your Mother actor wrote and directed the independent film, which also stars Elizabeth Olsen.
Liberal Arts was one of 14 movies from this year's Sundance Film Festival to come to London's Sundance festival last weekend.
The film centres around Jesse (Radnor), a single man in his mid-30s who struggles to deal with growing older and gaining extra responsibilities. He revisits his college days at a retirement dinner where he meets a beautiful sophomore (Olsen), which brings out forgotten emotions and hopes.
IFC Films has picked up the movie for North American distribution this autumn, while Revolver Entertainment and Picturehouse Entertainment have purchased it for its UK release in the autumn.
Liberal Arts also stars Richard Jenkins, Allison Janney, Zac Efron and Elizabeth Reaser.
Radnor's first movie project was 2010's Happythankyoumoreplease, which received the Sundance Audience Award.
The actor will continue his role as Ted Mosby in How I Met Your Mother's seventh season finale on May 14 on CBS.