Kyösti (originally Gustaf) Kallio was born 1873 in Ylivieska, Finland. His father was a farmer and a prominent local politician. He joined newly founded Agrarian Party 1906 and he became one of its prominent leaders. He became an agrarian minister in the Senates of Oskari Tokoi, Pehr Evind Svinhufvud and Juho Kusti Paasikivi. During the Civil War in Finland, he hid in Red-dominated Helsinki because he was at least nominally on the White side and therefore a "class enemy" and formed a new senate in Helsinki after German troops had defeated the Reds in the city. Afterwards he became a moderate peace-maker and disapproved of retaliation against the Reds.
During the debates over the form of the new state in 1918, Kallio resigned from the Senate because he supported a republic instead of constitutional monarchy. Eventually, the monarchist stand lost and he returned to Cabinet to become Prime Minister. He was a reformist who emphasized education, settlement and land reform. His greatest achievement was "Lex Kallio" in 1922, a legislation allowing the state to buy land to encourage new settlements. On the other hand, he did support Prohibition in Finland, and was dismayed when it was repealed in 1932.
Kallio was an anti-communist suppressing the Finnish Communist Party (SKP) in 1923, but he resorted to legislative methods. When the violent right-wing Lapua Movement asked him to become their leader, he refused and was instead subjected of their death threats.
Kallio was elected president with the votes of conservative and social democratic coalition that wanted to ensure that President Svinhufvud would not be re-elected. Kallio took a role of a parliamentarian president and avoided use of his personal power.
In the eve of Winter War, when Carl Gustaf Mannerheim once again threatened to resign due to schism with the Cabinet, Kallio convinced him to stay. During the war he resisted the idea to give up any territory to the Soviet Union, but was forced to agree to sign the Moscow Peace Treaty. His health begun to fail – his right arm was paralyzed – and he was not active in the dealings with Germany leading to the Continuation War. On August 28 he suffered a serious stroke, and the Prime Minister Risto Ryti took over his duties.
Kallio resigned formally on November 27, 1940, prior to the Continuation War. He was going to Nivala to his farm after the farewell ceremonies, when he collapsed and died at the Helsinki railway station, before the guard of honor and Marchal Mannerheim.