Yrjö Leino (28 January 1897, Helsinki, Finland – 28 June 1961, Helsinki) was a Finnish communist politician. Imprisoned twice for his communist activities, and spending much of the Second World War as an underground communist activist, he served as a minister in three cabinets between 1944 and 1948.
Yrjö Leino was the only child of tanner Oskar Leino and factory worker Mandi Leino (née Enfors). Leino studied at Helsingin normaalilyseo without graduating. In 1921, after working in Helsinki and in casual agricultural jobs, Leino received an agricultural trade school diploma. Around 1924, Leino bought a farm called Lövkulla in Kirkkonummi, but the farm soon led him to financial difficulties. Leino was forced to sell Lövkulla in the early 1930s. Around this time he also separated from his first wife, Alli Simola, and moved to Oitmäki, where his second wife Ulla Smedberg was a teacher. Again, the marriage ended in separation.
Leino moved towards the extreme left in the 1930s. Detectives had begun surveillance on him after the fugitive communist activist Antti Järvinen had visited Leino in Lövkulla in early 1926. The same year Leino was also visited by Arvo Tuominen, who had just been released from prison. In 1935, Leino was sentenced to three and a half years' imprisonment for high treason. During imprisonment at the Tammisaari prison camp, he is said to have formally become a communist. Leino was released from prison in 1938, but the security police Valpo kept him under surveillance. The newly liberated Leino then participated in underground activities of the prohibited Communist Party of Finland.
During the Winter War Leino stayed underground, hiding in communist safe-houses across the Finnish countryside. In those years, Leino became acquainted with his future wife Hertta Kuusinen. In 1940, Leino was detained in a secure facility. His detention continued until 1941, when he escaped from a prison train in Riihimäki, which was taking prisoners to fight in a penal battalion. Leino participated in underground Communist Party activities until the 1944 armistice between Finland and the Soviet Union and the legalization of the Communist Party.