Canadian politician who twice served as premier of Saskatchewan (1926–29 and 1934–35).

After working on a farm in Manitoba from 1901, Gardiner in 1904 moved to Saskatchewan, where he became a schoolteacher and principal. He became a Liberal member of the Saskatchewan Legislative Assembly in 1914 and sat until 1935. After being appointed to the provincial Cabinet in 1922, he succeeded C.A. Dunning as premier in 1926. His party lost the 1929 election but returned in 1934, with Gardiner again as premier.

He resigned as premier the following year to become federal minister of agriculture and was elected to the dominion House of Commons for Melville. Gardiner was minister of agriculture during W.L. Mackenzie King's and Louis Saint Laurent's ministries for 22 years. He dealt with federal agricultural assistance during the Great Depression of the 1930s and with problems relating to World War II (1939–45). In 1947 he was appointed to the Imperial Privy Council and made an unsuccessful attempt to replace King as Liberal leader. Reelected to the House in 1957, Gardiner resigned his portfolio when the Liberal ministry resigned.