Asner was born Eddie Asn. in Kansas City, Missouri, but was raised in nearby Kansas City, Kansas. His Russian-born parents, Lizzie (née Seliger), a housewife, and Morris David Asner, ran a second-hand shop. He was raised in an Orthodox Jewish family. Asner attended Wyandotte High School and the University of Chicago. He served with the U.S. Army Signal Corps and appeared in plays that toured Army camps in Europe.
Following his military service, Asner joined the Playwrights Theatre Company in Chicago, but left for New York before members of that company regrouped as the Compass Players in the mid-1950s. He later made guest appearances with the successor to Compass, The Second City, and is considered part of The Second City extended family. In New York, Asner played Jonathan Jeremiah Peachum in the acclaimed Broadway revival of Threepenny Opera, and began to make inroads as a television actor.
Before he landed his role with Mary Tyler Moore, Asner guest-starred in such television series as NBC's The Outlaws (1962), in the series finale of CBS's The Reporter, Mission: Impossible and The Invaders.
Asner is best known for his character Lou Grant, who was first introduced on The Mary Tyler Moore Show in 1970. In 1977, after the end of the Mary Tyler Moore show, Asner's character was given his own show, Lou Grant, which ran from 1977-1982. In contrast to the Mary Tyler Moore show, which was a thirty minute comedy, the Lou Grant show was an hour long award-winning drama about journalism. (For his role as Grant, Asner is the only actor to win the Emmy award for a sitcom and a drama for the same role.) Other TV series starring Asner in regular roles include Thunder Alley, The Bronx Zoo, and Studio 60 on the Sunset Strip. He also portrayed diamond smuggler August March in a 1975 episode of the original Hawaii Five-O and, recently, he reprised the role in the Hawaii Five-0 remake.
Asner was acclaimed for his role in the miniseries Roots, as Captain Davies, the man who kidnapped Kunta Kinte and sold him into slavery, despite his own moral conflicts. The role that earned Asner an Emmy Award, and for a similarly dark role as Axel Jordache in the mini-series Rich Man, Poor Man. In contrast, he played Pope John XXIII in Papa Giovanni: Ioannes XXIII, an Italian miniseries for RAI.
Asner has also had an extensive voice acting career. He provided the voices for J. Jonah Jameson on the 1990s animated television series Spider-Man, Hudson on Gargoyles, Jabba the Hutt on the radio version of Star Wars, Master Vrook from Star Wars: Knights of the Old Republic and its sequel, Roland Daggett on Batman: The Animated Series, Cosgrove on Freakazoid!, Ed Wuncler on The Boondocks, and Granny Goodness in various DC Comics animated series. Asner has also provided voice-over narration for many documentaries and films of social activism.
More recently, Asner provided the voice of Carl Fredricksen in the Academy Award winning 2009 Pixar film Up. He received great critical praise for the role, with one critic going so far as to suggest "They should create a new category for this year's Academy Award for Best Vocal Acting in an Animated Film and name Asner as the first recipient."
He has appeared in a recurring segment, on Jay Leno's The Tonight Show, entitled "Does This Impress Ed Asner?"
He was cast in a Country Music Television comedy pilot, Regular Joe.
In 2001, Asner was the recipient of the Screen Actors Guild Life Achievement Award.
Asner has won more Emmy Awards for performing than any other male actor (seven, including five for the role of Lou Grant). In 2003, he was inducted into the Academy of Television Arts & Sciences Hall of Fame.
In July 2010, Asner completed recording sessions for Shattered Hopes: The True Story of the Amityville Murders which is a forthcoming documentary on the 1974 DeFeo murders in Amityville, New York. Asner serves as the narrator for the film, which covers a forensic analysis of the murders, the trial in which 23-year old DeFeo son Ronald DeFeo Jr., was convicted of the killings, and the subsequent "haunting" story which is revealed to be a hoax. In January 2011, Asner took a supporting role on CMT's first original sitcom Working Class. He made an appearance in the independent comedy feature Not Another B Movie, and had a small but pivotal role as billionaire Warren Buffett in HBO's 2011 economy drama Too Big to Fail .