He is best known for his work in theatre as well as television series such as The Sopranos, Bones, Grey's Anatomy, Parks and Recreation, and Rizzoli & Isles as well as films, including The Island and The Producers.
Smagula made his professional acting debut at age 20 in the Paper Mill Playhouse production of Man of La Mancha.
From 2011 to 2016, Smagula appeared in television shows including Hot in Cleveland, Grey's Anatomy, Jessie, Betty White's Off Their Rockers, Parks and Recreation, Sam and Cat, Brooklyn Nine-Nine, Rizzoli and Isles, Community, and Bones.
In 2017, Smagula played John Woodburn in the film Rebel in the Rye, written and directed by Danny Strong and starring Kevin Spacey and Nicholas Hoult.
[8] In 2023, he played the dual role of Mr./Billy Webster in Stephen Sondheim and James Lapine's Sunday in the Park with George at the Pasadena Playhouse.
He also played Sir Bedevere in the Kennedy Center production of Spamalot and reprised the role in the Broadway revival at the St. James Theatre.