Born Mar. 24, 1902, in Kaukola, now in Leningrad Oblast, RSFSR. Finnish labor leader; activist in the international labor movement.
Until 1924, Pessi worked at lumbering and in industrial enterprises in southeastern Finland, and from 1924 to 1927 he worked at railroad workshops in Pasila, a section of Helsinki. In 1923 he joined the Socialist Union of Youth, and in 1924 the Communist Party of Finland (CPF). Pessi became secretary of the party organization of railroad shopworkers of Pasila and subsequently a professional revolutionary. In 1930 and 1931 he worked as an underground organizer of regional committees of the CPF in the cities of Vaasa and Turku. In 1931 he became a member of the Central Committee (CC) of the CPF and in 1932-33 served as secretary of the CC for organizational work. After the arrest of T. Antikainen by the Finnish secret police in 1934, Pessi headed the Communist Party. From 1935 to 1944 he was incarcerated in prisons and concentration camps for his communist activities. From 1944 to 1972, Pessi was a member of the Politburo of the CC of the CPF. From 1944 to 1969 he was also general secretary of the CC of the CPF, and in April 1972 he was elected an honorary chairman of the CPF. From 1945 to 1966 he was a member of parliament. Pessi was awarded the Order of the October Revolution in 1972.