Hart was born to a poor Saskatchewan family but became a successful amateur wrestler during the 1930s and early 1940s, holding many championships and staying undefeated for extensive periods, as well as engaging in many other sports. He began wrestling for show in 1943 with the Royal Canadian Navy while serving under World War II. After leaving the navy he traveled to America and debuted professionally for the New York wrestling territory in 1946. Hart was considered very handsome and a good in-ring performer, focusing on an submission-like and technical style of wrestling, despite this and being popular in general he was not given major spotlight by the writers and after marrying Helen Smith whom he met in New York City, he moved back Canada and created his own promotion which would be known as Stampede Wrestling and took over the surrounding wrestling territory that covered most of western Canada. The territory would go on to become known as the Stampede territory thenceforth. Hart's promotions featured a large variety of outside stars from the wrestling industry as well as homegrown talents for whom he booked storylines. Beginning from the 1950s Hart helped train an large amount of people for his company and gained a reputation as one of the best teachers in the wrestling business.
Hart remained an active full time wrestler until the 1960s when he entered semi-in-ring retirement, thereafter he would focus mostly on promoting, booking and teaching, as well as raising his twelve children with Smith while still appearing in the ring sporadically until the 1980s. Throughout his career, Hart almost exclusively portrayed a heroic character, a so-called "babyface" role and only held one professional title, the NWA Northwest Tag Team Championship. After selling his territory to Titan Sports, Inc. in the mid 1980s, Hart would make several appearances on WWF television and Pay-Per-View with his wife, often involved in storylines surrounding his sons Bret and Owen and several of his sons-in-law who were signed to the company. He continued to teach wrestling at his home in Calgary until the 1990s when he suffered a leg injury and had to stop engaging excessively with students, leaving most work for his sons Bruce and Keith. He died at age 88 after suffering from multiple medical issues.
Hart has been referred to by multiple writers, including wrestling historian Dave Meltzer, as one of the most influential and important figures in pro wrestling history. His greatest contribution to the art was as a promoter and trainer. Along with Bret and Owen, Hart's trainees included future world champions Fritz Von Erich, Superstar Billy Graham, Chris Jericho, Edge, Christian, Mark Henry, Chris Benoit, and Jushin Thunder Liger. Hart was a member of the inaugural Wrestling Observer Newsletter Hall of Fame class in 1996 and was inducted into the WWE Hall of Fame in 2010 by his son Bret. Hart was also well known for his involvement in over thirty charities, for which he was given a position in the Order of Canada, the second highest honour for merit that can be given in Canada and the second highest civilian honour.
He was born in Saskatoon in 1915 to Edward and Elizabeth Stewart Hart. He was mainly of Scots-Irish descent but also had Scottish and English ancestry.
His childhood was impoverished; as a boy, Stu Hart lived in a tent with his family on the prairie in Alberta, living off the land, milking cows and wild game that Stu took down with his slingshot. As a child Hart and his sisters were often mistreated at school by both fellow students and teachers since it was well known that they were from such a poor family. Hart was also berated and treated with disdain for being lefthanded, something seen as deviant at the time. Like most lefthanded children at the time, he was forced to work with his right, and as a result he became ambidextrous. In 1928, his father was arrested for failure to pay back taxes, while the Salvation Army sent Stu, his mother, and two sisters, Sylvester and Edrie to live in Edmonton. Due to his destitute childhood and youth Hart did not experience a dramatic shift in life quality or mentality during the Great Depression which affected most others around him in Edmonton.