Walsh studied theatre in Toronto at Ryerson University but dropped out to work with the CODCO comedy troupe on a series of stage shows, which eventually evolved into a sketch comedy series. The CODCO series ran from 1987 to 1992 on CBC Television.
''This Hour Has 22 Minutes''
In 1992, she began to work with former co-star Rick Mercer and former CODCO co-stars Cathy Jones and Greg Thomey to create a new television series called This Hour Has 22 Minutes. The show would be a parody of the nightly news and would poke fun at Canadian and international politics. 22 Minutes received strong ratings during its earlier seasons and Walsh's character Marg Delahunty became famous for buttonholing politicians and submitting them to satirical interviews. Usually Marg Delahunty would recite a scripted piece intended to humiliate the politician, often by providing criticism and "grandmotherly" advice. Sometimes Marg appeared as "Marg, Princess Warrior", a parody of the title character of portrayed by Lucy Lawless. Walsh is also noted for her comical segment chronicling the Canadian Auto Workers Union's tense blockade of the Volvo Halifax Assembly plant in 1998. In 2007, she revived Marg Delahunty for the Royal Canadian Air Farce's 300th episode. On October 24, 2011, Walsh was once again in the spotlight as she reprised the role of Marg Delahunty conducting an ambush interview of Toronto Mayor Rob Ford at his home. Ford's reaction and alleged verbal abuse directed at 911 operator made national headlines. She also reprised her role as Marg, Princess Warrior for an episode of 22 Minutes' 25th season in December 2017.
Other work
Walsh's other television work included the short-run sitcoms Dooley Gardens in 1999, Hatching, Matching and Dispatching and she had a guest starring role as Miranda Cahill on the CBC television series, Republic of Doyle. She currently has a recurring role on CBC's Little Dog. She created the CBC program , a talk show about books and literature, in 2003. Walsh revived the Fury family from Hatching, Matching, and Dispatching by writing and starring in A Christmas Furyin 2017. Besides TV acting, she has worked on movies such as Mambo Italiano, Geraldine's Fortune, Rain, Drizzle and Fog, Buried on Sunday, The Divine Ryans, Young Triffie,Violet,and The Grand Seduction. 2004 saw Walsh host a segment on the CBC documentary seriesThe Greatest Canadian, in which she championed the case for Sir Frederick Banting as the greatest Canadian who ever lived. In June 2007, she hosted the Pride Toronto Gala & Awards ceremony. On December 15, 2007, Walsh made national news with a story about her upcoming special, Nudity, Sexuality, Violence and Coarse Language, in which a large group of people who went and stripped naked standing next to St. John's Harbour in −11° Celsius temperature to be filmed as a part of the show's closing. Walsh herself did not go nude. In 2017, Walsh published her debut novel, Crying for the Moon.
Directing
Walsh made her feature directorial debut with the 2007 movie Young Triffie. She was the first Newfoundlander in six years to have a film in general release across Canada.
Personal life
Walsh has battled alcoholism. The Toronto Star reported that the end of CODCO coincided with the end of Walsh's active alcoholism, with Walsh stating "which was a damn good thing because I could have never done This Hour Has 22 Minutes if I'd been drinking."
A sufferer of macular degeneration, she has served from time to time as a spokesperson for the Canadian National Institute for the Blind. In 1993, Walsh was chosen to deliver the prestigious Graham Spry lecture which was broadcast nationally on CBC Radio. In 1994, Walsh addressed the United Nations Global Conference on Development in New York. She has also served as a spokesperson for Oxfam, Canada's human rights campaign, and in 2010 received Oxfam's Spirit of Change Award, in recognition of her years of dedication to eradicating poverty and ensuring public services for all. On May 29, 1998, Mary Walsh received an Honorary Doctor of Laws from Trent University. McGill University honoured Walsh with an honorary doctorate during the November 2008 convocation ceremony. Her speech to the class of 2008 focused on political satire.
