Breuer first rose to fame as a cast member of Saturday Night Live from 1995 to 1998. On SNL, Breuer's characters included "Goat Boy" (who hosted the fictional MTV program "Hey, Remember the 80s?") and Glen Henderson, the elder brother to Chris Kattan's Todd Henderson/Azrael Abyss character in the "Goth Talk" skits. He was originally scheduled to have been the co-star alongside friend and co-worker Dave Chappelle in the 1996 ill-fated sitcom "Buddies," but was pulled from the role. Subsequently, the show was unsuccessful and stopped airing after the fifth episode. Among his impersonations was that of actor Joe Pesci, who hosted his own talk show, often accompanied by Colin Quinn playing fellow actor Robert De Niro. In a 1997 episode of the program, both Pesci and De Niro made surprise appearances to "confront" Breuer. Breuer is the new host of the third season of the VH1 show Web Junk 20. The season began on November 17, 2006. He replaces Patrice Oneal, who hosted the first two seasons of the show.

Breuer was a sit-in comedian on the Opie and Anthony Show for many years during their WNEW tenure. "Breuer Bits" were often played whenever the show was on hiatus. Breuer is the host of Breuer Unleashed, which can be heard regularly on weekdays on the Sirius Satellite Radio channel "Raw Dog Comedy." His co-host is Pete Correale. He credits XM radio host Ron Bennington, of The Ron and Fez Show, for helping get his career started.[citation needed] One show, while Breuer was singing the classic Judas Priest song "Devil's Child," Rob Halford "The Metal God," singer of Judas Priest, entered the studio still with his coat on and sang with him. He is an occasional guest on the Mancow Show and the Howard Stern show. He has previously guest starred in Home Improvement.

On July 17th, Jim Breuer performed his Brian Johnson signature "Hokey Pokey" with the actual Brian Johnson from AC/DC. Jim then went on to sing "Hey, Hey, Who Phoned The Law" right after the two went back and forth singing the Hokey Pokey.

Jim Breuer appeared in the film Half Baked as the character Brian.