She was born in South Dumfries Township, Ontario, the daughter of Isabella Bowie and James Flett. She left Woodstock, Ontario in 1912 for Winnipeg with her mother and sister Lynn. She worked there as a public stenographer. Flett and her sister helped found the Political Equality League (later the Manitoba Political Equality League), whose aim was to gain the vote for women in the province. She was in charge of a petition organized by this group which bore the signatures of 39,584 women. In January 1916, Manitoba became the first province in Canada to grant women the vote.