The pair is engaged, Seyfried's publicist Evelyn Karamanos confirmed to USA TODAY, after a whirlwind romance that began this spring.
The two actors started dating while filming their upcoming drama, The Last Word.
Seyfried, 30, and Sadoski, 40, first met on Broadway in 2015 as co-stars in The Way We Get By, a
This will be Seyfried's first marriage, with the star previously dating
Sadoski, currently starring in CBS' Life in Pieces, filed for divorce with his previous wife of eight years, Kimberly Hope, in fall 2015.