Harry Shearer began his career as a child actor in 1950s movies ("The Robe") and television ("The Jack Benny Program"). Shearer also played the precursor to the Eddie Haskell character in the pilot episode of the TV series "Leave It to Beaver." Shearer was later a member of Los Angeles radio comedy group "The Credibility Gap," 1968–1974, and a writer for such television shows as "Fernwood 2-Night" and "Laverne and Shirley." In August 1979, Shearer was hired as a writer and cast member on "Saturday Night Live," an unofficial replacement for John Belushi and Dan Aykroyd, who were both leaving the show. According to the book "Saturday Night: A Backstage History of Saturday Night Live," Shearer did not get along well with the other writers and castmembers, who regarded him as "prickly." His first tenure on the show ended when Lorne Michaels left SNL, taking the entire cast with him. Shearer returned to Saturday Night Live in the 1984–1985 season, leaving for good in January 1985 over "creative differences." When reached for comment over the nature of his departure, Shearer replied "I was creative; they were different".

Shearer co-created, co-wrote and co-starred in Rob Reiner's 1984 film "This Is Spinal Tap" with Michael McKean and Christopher Guest; the three of them also collaborated on the acclaimed 2003 spoof "A Mighty Wind," which was written by Guest and Eugene Levy, and directed by Guest. Shearer's television work also includes two specials for Cinemax, "It's Just TV", and "This Week Indoors" (co-created with Merrill Markoe) and "The Magic of Live". He directed the entire six-episode cable series, "The History of White People in America", co-created by Martin Mull and Allen Rucker, as well as the two-hour feature finale of the series, "Portrait of a White Marriage". He also co-wrote and directed Paul Shaffer's fantasy special for HBO, "Viva Shaf Vegas" (with Shaffer and Tom Leopold). His first theatrical feature, which he wrote and directed, was "Teddy Bears' Picnic", a dark comedy loosely based on the workings of Bohemian Grove, the secret retreat of the elite.

Shearer has three books published, "Man Bites Town" (a collection of his Los Angeles Times Magazine columns), "It's the Stupidity, Stupid", and "Not Enough Indians", a comic novel about Native Americans and gambling.

Shearer may be best known for his prolific work as a voice actor on "The Simpsons" (1989 to present), where he provides voices for Mr. Burns, Waylon Smithers, Ned Flanders, Reverend Timothy Lovejoy, Kent Brockman, Dr. Julius Hibbert, Dr. Marvin Monroe, Lenny Leonard, Principal Seymour Skinner, Otto Mann and Rainier Wolfcastle among others. He was one of three Simpsons voice actors to guest star on the show "Friends" ("The One With the Fake Monica"); the other two were Dan Castellaneta and Hank Azaria. He also appeared in "Godzilla" with Hank Azaria, which had a cameo appearance from Nancy Cartwright, the voice of Bart Simpson. In a 2004 interview, Shearer stated that he thought the show was declining in quality with each passing season (starting in its fourth season). He rated the last three seasons (at the time being seasons 13, 14, and 15) as "the worst yet". He did admit that he had not watched older episodes that much, being focused on the recent ones.

Since 1983, Shearer has been the host of the public radio comedy/music program "Le Show" on Santa Monica NPR affiliated radio station KCRW. The show is podcast and airs on public radio stations throughout the country. He is the regular announcer for TV Land and since May 2005 has been a contributing blogger at The Huffington Post. Shearer has homes in both Santa Monica, California and the French Quarter of New Orleans, Louisiana. According to a telephone call on "Ask Mr. KABC," his house survived Hurricane Katrina.

Shearer is recording for a BBC Radio 4 sitcom with Brian Hayes called "Not Today, Thank You." He plays a character named Nostrils, a man so ugly he can't stand to be in his own presence. He resides in washed up radio presenter Brian Hughes' (played by Hayes) garage (in the house belonging to his grandmother), sometimes appearing in other rooms of the house. On October 30, 2006, he appeared on Graham Norton's "Bigger Picture" in the UK. Read more on Last.fm. User-contributed text is available under the Creative Commons By-SA License; additional terms may apply.