NEW YORK—The cast album for "Once" has nabbed a Grammy Award, the latest honor for a show that has already earned a Tony and an Oscar.

The recording from the stage version of the movie won the best musical theater album Sunday, besting the cast albums from "The Gershwins' Porgy and Bess," the revival of Stephen Sondheim's "Follies," Disney's "Newsies" and another CD of Gershwin songs from the show "Nice Work If You Can Get It."

The musical starring Steve Kazee and Cristin Milioti is based on the low-budget 2006 film about an unlikely romance between a Czech flower seller and an Irish street musician in Dublin. Made for about $150,000, the original film earned $20 million.

It won the Tony for best musical last year, recouped its $5.5 million investment in less than six months, and triggered a national tour that will launch this summer.

"Never in my life could I have ever dreamed this. Stunned right now," Kazee tweeted Sunday after the Grammy win.

The film and musical feature songs by Marketa Irglova and Glen Hansard, including "Falling Slowly," which won an Oscar for best original song in 2007.

In an odd twist, the cast album of the musical won a Grammy but the original songs by Irglova and Hansard, which got Grammy nods in 2008 for best song and best album for a movie, eventually lost.