Bennett was born in Hopewell Hill, New Brunswick, and grew up in nearby Hopewell Cape. He studied law at Dalhousie University, graduating in 1893, and in 1897 moved to Calgary to establish a law firm in partnership with James Lougheed. Bennett served in the Legislative Assembly of the Northwest Territories from 1898 to 1905, and later in the Alberta Legislature from 1909 to 1911. He was the inaugural leader of the Alberta Conservative Party from 1905, resigning upon his election to the House of Commons in 1911.
From 1920 to 1921, Bennett was Minister of Justice under Arthur Meighen. He also served briefly as Minister of Finance in Meighen's second government in 1926, which lasted just a month. Meighen resigned the Conservative Party's leadership after its defeat at the 1926 election, with Bennett elected as his replacement (and thus Leader of the Opposition). Bennett became prime minister after the 1930 election, where the Conservatives won a landslide victory over Mackenzie King's Liberal Party. He was the first prime minister to represent a constituency in Alberta.
The main difficulty during Bennett's prime ministership was the Great Depression. He and his party initially tried to combat the crisis with laissez-faire policies, but these were largely ineffective. However, over time Bennett's government became increasingly interventionist, attempting to replicate the popular "New Deal" enacted by Franklin Roosevelt to the south. This about-face prompted a split within Conservative ranks, and was regarded by the general public as evidence of incompetence. Bennett consequently suffered a landslide defeat at the 1935 election, with Mackenzie King returning for a third term.
Bennett remained leader of the Conservative Party until 1938, when he retired to England. He was created Viscount Bennett, the only Canadian prime minister to be honoured with elevation to the peerage. Bennett's prime ministership is widely regarded as a failure by historians, although he left lasting legacies in the form of the Canadian Broadcasting Corporation (established 1932) and the Bank of Canada (established 1934).
Bennett was born on 3 July 1870, when his mother, Henrietta Stiles, was visiting at her parents' home in Hopewell Hill, New Brunswick, Canada. He grew up nearby at the Bay of Fundy home of his father, Henry John Bennett, in Hopewell Cape, the shire town of Albert County, then a town of 1,800 people.