He was born in Chicago, Illinois and attended Campion High School in Prairie du Chien, Wisconsin (the same school attended by Vicente Fox, Congressman Leo Ryan, and Wisconsin governor Patrick Lucey). He was kicked out of University of Notre Dame after a lack of studying resulted in a semester with a 0.00 GPA. A resident of the infamous party house Zahm House, he was known more for his all-night gallivanting than fastidious study habits. He was more successful at the Jesuit Rockhurst College in Kansas City where after applying himself, he graduated with a B.A. in Economics.

He is also an alumnus of The Second City which he discovered shortly after college. A viewing had inspired him to join and on his first day of employment, he showed up promptly at 11:30AM like he was instructed. The woman working there had handed him a broom and said "Welcome to the theater, kid." just as his first job in showbiz was sweeping up cigarette butts off the floors. Second City was also where he met his future wife, Bernadette Birkett, who was to later play the voice of Norm's never-seen wife, Vera, on Cheers.

In 1989, Wendt appeared as the eponymous protagonist in a BBC TV dramatization of Ivan Goncharov's novel Oblomov. He has also appeared twice (two episodes were made from one day's filming) on the British edition of Whose Line Is It Anyway?.

Wendt was the host of the A&E reality show, House of Dreams in 2004.

In January 2006, Wendt will be seen again on television screens as part of the cast of Modern Men.