French Stewart studied at the American Academy of Dramatic Arts and toured in regional theater for before getting his big break with the role of Razor Dee, a spaced-out DJ on the final season of The New WKRP in Cincinnati. A few years later, he was cast in the role of Harry Solomon on 3rd Rock from the Sun. On the show, he was noted for his talents at physical comedy and his characteristic "squinting" expressions.

In addition to 3rd Rock, Stewart has had a number of roles on other TV shows. His work includes Just Shoot Me, The Drew Carey Show, Less than Perfect and That 70's Show. He also starred in the WB Hit Charmed. Stewart has also appeared in a slew of major motion pictures including Leaving Las Vegas, Glory Daze, McHale's Navy, Love Stinks and Clockstoppers.