Leivo-Larsson was Deputy Minister of Social Affairs and Social Affairs in 1948–1950 at the Fagerholm I, Törngren and Kekkonen V 1954–1956 and in 1958 in Kuuskoski and Fagerholm II Governments as Social Minister in 1954–1954 and 1956–1957.
She was first elected to the Parliament from the Social Democratic Party in 1948–1958 and then as a member of the Social Democratic Union of Workers and Smallholders party for the years 1966–1970. During this time she was chairman of the Social Democratic Union of Workers and Smallholders Parliamentary Group. She married Bror Nils Larsson in 1937.
Tyyne Leivo participated at the Red Guard side at the age of 16 in the civil war in the Battle of Tampere. Possibly, she was in the group that at the last moment broke out of the city. Poet Kössi Kaatra describes her as a young, ready-to-fight youth who also dared drive the wounded.
In the Parliament, Leivo-Larsson was a member of the Committee on Banking, Labor and Subcommittee on Foreign Affairs. She was also a member of the Finnish delegation of the Nordic Council.