Chow is a former Canadian politician who served as federal New Democratic Party Member of Parliament for Trinity-Spadina from 2006–2014, and Toronto city councillor from 1991 to 2005. Chow is the widow of former NDP and Opposition Leader Jack Layton; they were married from 1988 until his death from cancer in 2011. She was a candidate in the 2014 Toronto mayoral election, where she placed third behind winner John Tory and runner-up Doug Ford.
Chow won the Trinity—Spadina riding for the New Democratic Party on January 23, 2006, becoming a member of the House of Commons of Canada. In 2011, she was re-elected in her riding for her third straight win. She speaks Cantonese, Mandarin and English. In May 2012, Chow was named one of the top 25 Canadian immigrants in Canada by Canadian Immigrant magazine. Chow's personal memoir, titled My Journey, was published January 21, 2014. Chow resigned her seat in parliament on March 12, 2014, to run in the 2014 Toronto mayoral election. Following her mayoral election loss, Chow became a distinguished visiting professor at Ryerson University from 2015 to 2018.