Short, youngest of five children, was born in Hamilton, Ontario, Canada, the son of Olive (née Hayter), a violinist, and Charles Patrick Short, a corporate executive with Stelco, a Canadian steel company. Short's father came to North America in 1921 as a stowaway Roman Catholic refugee from South Armagh, Northern Ireland during the Irish War of Independence.[citation needed] His mother, who was the concertmaster of the Hamilton Symphony Orchestra, encouraged his early creative endeavours.

Short attended Westdale Secondary School and graduated in 1972 from McMaster University with a Bachelor of Arts degree in social work.[4] Short lost several members of his family at an early age. His eldest brother, David, was killed in a car accident in 1962, when Short was 12. His mother died of cancer when he was 17; two years later, his father died of complications from a stroke in 1970.[5]

When Short graduated from McMaster University, he intended to pursue a career in social work, but he became interested in acting once he was cast in a Toronto production of Godspell in 1972 (among the other members of that production's cast: Victor Garber, Gilda Radner, Eugene Levy, Dave Thomas and Andrea Martin, with Paul Shaffer as musical director.) He was subsequently cast in several television shows and plays, including an intense topical drama, Fortune and Men's Eyes. (He worked solely in Canada from 1972 through 1979.)

In 1979, Short starred in the ill-fated TV sitcom The Associates about a group of young novice lawyers working at a Wall Street law firm. The show was cancelled after only 9 of the 13 episodes were aired, but received 2 Golden Globe nominations after its cancellation.

Short then joined the cast of I'm A Big Girl Now, a sitcom vehicle for Diana Canova that also starred Danny Thomas, in 1980. Canova was offered the sitcom due to her success playing Corinne Tate Flotsky on ABC's Soap, and she left the cast of the latter show in the fall of 1980 in order to accept the offer shortly before Short's newlywed wife Nancy Dolman joined it.

Short was encouraged to pursue comedy by McMaster classmates Eugene Levy and Dave Thomas, both notable comedians in their own right. He joined Levy and Thomas at improv troupe The Second City in 1977. Short came to public notice when the troupe produced a show for television, called SCTV (Second City Television), which ran for several years in Canada and the United States. Short was a cast member and performed several recurring characters. He was a member of the troupe for several years before moving on to Saturday Night Live for the 1984-1985 season.[6] At SCTV, Short developed many characters which he later used at SNL:

• Talk show host Brock Linehan, based on the Canadian interviewer Brian Linehan.
• Aged songwriter Irving Cohen
• Spurious albino entertainer Jackie Rogers, Jr.
• Current-events commentator Troy Soren
• Industrialist and art patron Bradley P. Allen
• Defensive attorney Nathan Thurm
• Oddball man-child Ed Grimley
• Hollywood agent and man-about-town Jiminy Glick.

At SNL, Short helped revive the show after Eddie Murphy left with his many characters, including the Wheel of Fortune fan Ed Grimley he borrowed from his SCTV days. The Grimley character became perhaps Short's best known original character. He also was recognized for his impersonations of celebrities, notably Jerry Lewis and Katharine Hepburn, and for the character of Nathan Thurm. SNL proved to be the springboard to a long career in film & TV.

After doing sketch comedy for several years, Short focused on film roles, appearing in several films, including Three Amigos, Innerspace, Captain Ron and the 1991 remake of Father of the Bride. In 2004 he wrote and starred in Jiminy Glick in Lalawood, with Jan Hooks as his improbable wife, Dixie Glick.

Short also resumed work in the theater, taking a role in the 1993 musical version of the Neil Simon work The Goodbye Girl. He had the lead role in the 1999 revival of the musical Little Me, which earned him a Tony Award.

Short performed in a satirical one-man show (with a full cast of six), Martin Short: Fame Becomes Me, at the Bernard B. Jacobs Theatre on Broadway. The show toured several cities in the spring of 2006, began previews on July 29, 2006, opened on August 17 and closed on January 7, 2007. In it, he performed his aforementioned classic characters Grimley, Cohen, and Glick. As Glick, Short brought a member of the audience (usually a celebrity) on stage and interviews him or her. Jerry Seinfeld was the guest on opening night and the subjects have included Kristin Chenoweth, Regis Philbin, Neil Simon, Diane Keaton, Jamie Lee Curtis, Richard Kind, David Schwimmer, David Hasselhoff and many more. The show also featured parodies of many celebrities including Celine Dion, Katharine Hepburn, Elizabeth Taylor and Richard Burton, Tommy Tune, Joan Rivers, Britney Spears, Ellen DeGeneres, Renée Zellweger, Jodie Foster and Short's wife, actress Nancy Dolman.

The cast album was released on April 10th, 2007 and is available from Ghostlight Records, an imprint of Sh-K-Boom Records.

During 2008 Short continues to tour his comedy show, which features many of his best loved characters and skits. While touring in Milwaukee Wisconsin he made a stop on a popular radio morning show with Dave & Carole & KB on 96.5 WKLH.

Short met Canadian comic actress Nancy Dolman during the run of the 1972 production of Godspell. After that production, Short dated costar Gilda Radner, then began dating Dolman (Radner's understudy) in 1974. The couple married in 1980. Dolman was most notable for her recurring role on the ABC cult sitcom Soap, SCTV, and Custard Pie.

Dolman retired from show business in 1985 to be a homemaker.[citation needed] Short and Dolman have three children: Katherine Elizabeth (born December 3, 1983), Oliver Patrick (born 1986), and Henry (born 1989). Short and his family make their home in Pacific Palisades, California, and Short has become a naturalized U.S. citizen. They also have a home on Lake Rosseau in Ontario, Canada.[7]

Short has a star on Canada's Walk of Fame.[8] A Roman Catholic, he is often incorrectly identified as Jewish.[3] His brother, Michael Short, is a comedy writer and twice winner of the Emmy Award for comedy sketch writing.

Dolman's brother, screenwriter/director Bob Dolman (who served as a part of SCTV's Emmy-winning writing team alongside Short), married their close friend and colleague Andrea Martin, also in 1980. Dolman and Short are aunt and uncle to the couple's two sons, Jack (born 1981) and Joe (born 1983). Bob Dolman and Andrea Martin have since divorced.[9] Short is the first cousin of Clare Short, a member of the British Parliament and a former British cabinet minister.