After attending Hudson River Military Academy, Seiter broke into films in 1915 as a bit player at Mack Sennett's Keystone Studios, doubling as a cowboy.

In the early sound era, Seiter helped nurture the talents of RKO's comedy duo Wheeler & Woolsey in features such as Caught Plastered (1931) and Diplomaniacs (1933).

Seiter's other films include Sunny, Going Wild, Kiss Me Again, Hot Saturday, Way Back Home, Girl Crazy, Rafter Romance, Roberta, Susannah of the Mounties, Allegheny Uprising, You Were Never Lovelier, Up in Central Park, and One Touch of Venus.

For the 1938 feature Room Service, a stage play had already been adapted for the Marx Brothers, limiting the action to only a few sets and forcing Seiter to stick closely to the shooting script.

Seiter's distinctive directorial style was generally appreciated by critics (his work on the 1943 Jean Arthur-John Wayne romantic comedy A Lady Takes a Chance received raves), but his deliberate pacing was sometimes taken for slowness.