In 1987, Kramer made his first acting debut in television film The Gunfighters. He also starred in the 1990 film Quest for the Mighty Sword. He played Thor in the television movie The Incredible Hulk Returns and a Russian baseball player in the television movie The Comrades of Summer. Among Kramer's more notable roles have been Little John in Robin Hood: Men in Tights, Bear in American Wedding, and Boris, bodyguard to producer Lee Donowitz, in True Romance. He has also appeared in a number of notable television series, including Two and a Half Men, Wizards of Waverly Place, Growing Pains, Cheers, Empty Nest, CSI: Crime Scene Investigation, NewsRadio, JAG, Roseanne, Murder, She Wrote, Seinfeld, That '70s Show, Ellen, Monk, Jack and Bobby, Phil of the Future, How I Met Your Mother and My Name Is Earl. Kramer was also a series regular on the sitcom Bob as Whitey van de Bunt (1993) and the ABC/UPN sitcom The Hughleys as Dave Rogers.
Kramer continues to work on the stage as a member of the Antaeus Classical Rep Company in Los Angeles, and received an Ovatti Award nomination for his role in "The Wood Demon". He currently co-stars as Bob Duncan on the Disney Channel sitcom Good Luck Charlie.