The "Life in Pieces" actor revealed the surprising news on "The Late Late Show with James Corden."
"We eloped. We just took off into the country with an officiant and, just the two of us, and we did our thing," Sadoski said.
Sadoski and Seyfried are expecting their first child together. They first met in 2015 while performing in the theatrical production "The Way We Get By," but didn't begin dating until a year later. They reunited professionally for the movie "The Last Word," which hits theaters later this month.
"It was beautiful. It was everything that it should be," Sadoski said of their elopement, noting they wrote their own vows. "It was just the two of us talking to each other."
And of course, that's not the only big event taking place in the couple's lives — they've got a baby on the way! "I'm more excited about this than I've ever been about anything in my life. And I'm also more terrified about it than anything I've ever been in my entire [life.]"
Want more stuff like this? Like us on Facebook.