Love is spilling from stage to screen to the altar for Amanda Seyfried!

The actress is engaged to her stage and screen co-star, Thomas Sadoski, a rep for Sadoski confirms to ET.

Prior to the news, Seyfried was spotted wearing a sparkler on her ring finger while out and about in New York City on Sept. 6.

WATCH: Amanda Seyfried and 'Last Word' Co-Star Thomas Sadoski Are Dating

The couple met last year when they starred as lovers in the stage production, "The Way We Get By," in New York.

They then filmed the movie "The Last Word" earlier this year, with ET confirming in March that the pair had started dating.

NEWS: Amanda Seyfried Kisses New Boyfriend Thomas Sadoski During PDA-Filled Lunch Date

The 30-year-old "Mamma Mia!" actress previously dated actors Justin Long and Dominic Cooper, but has never been married.

"The Newsroom" star Sadoski, 40, split from his wife last year.