Nealon debuted on network television doing a stand-up routine for The Tonight Show Starring Johnny Carson in 1984.
Just two years later, Nealon joined the cast of Saturday Night Live, and remained for nine seasons.
Nealon's SNL characters include Mr. Subliminal (or Subliminal Message Man), Franz (of Hans and Franz) along with Dana Carvey, Mr. No Depth Perception, the anchor of Weekend Update (where he ended each edition with "I'm Kevin Nealon, and that's news to me"), and many others.
In 1991, he starred in the Christmas movie, All I Want for Christmas. More recently Nealon has appeared in the movies Happy Gilmore, Anger Management, Little Nicky, Daddy Day Care, Good Boy! and Grandma's Boy. In fall 2005, he appeared in an episode of Curb Your Enthusiasm, where he played himself (Season 5, Episode 4).
Nealon continues to make regular appearances in TV and film, while also touring the country performing stand-up.