Mauno Koivisto was born in Turku, Finland as a second son of a shipwright. His mother died when he was 10. At the beginning of the Winter War, when he was 16, he joined a field firefighter's unit. During the Continuation War, Koivisto served in the Infantry Detachment Törni, led by the later famous Lauri Törni.
After the war Koivisto became active in politics, joined the Social Democratic party and worked as a dockworker's representative. In 1949, he organized left-wing resistance against communist strike agitators who tried to take over the dockworker's union and indirectly threatened the stability of the government of Karl-August Fagerholm.
Later he worked as a school teacher and met Tellervo Kankaanranta, his future wife. He also finished his studies, graduating with a Bachelor of Arts in 1953. Three years later he completed his doctoral thesis about the social relations in the Turku dockyards.
In 1957, he became a banker, which eventually lead to a position as chairman of the board of the Bank of Finland. Meanwhile, he had to witness intra-party schisms in the Social Democratic party. He tried to improve the party's connections to communists and to president Urho Kekkonen. In 1968 he became Prime Minister of Finland.
In the 1970s, Kekkonen seemed to regard Koivisto as his potential rival and supported Kalevi Sorsa. Koivisto remained as the chairman of the Bank of Finland. In 1979, he was re-elected as prime minister and refused Kekkonen's demand that he resign. When Kekkonen resigned for health reasons, Koivisto became an acting president preceding elections.
During the campaign, Koivisto distanced himself from those with Moscow's backing. Polling percentage rose to 87% and his wife and daughter were the most popular electors. As president, he kept a low profile and used less authoritarian leadership tactics than Kekkonen had. On the other hand, he did not appreciate journalists, calling them "lemmings". As the leader of Finland's foreign policies he initially continued Kekkonen's line till the end of the crumbling Soviet Union. After that he supported more radical ideals like joining the European Union.
Koivisto's term ended in 1994. He has published his memoirs and continued as a commentator of economics.