Born in to a poor working-class family, Korsakas spent most of his childhood in Riga where his parents looked for work. He did not finish his secondary education and was expelled from his gymnasium for student activities. He started his literary activity in 1923 and wrote journalistic articles under the pseudonym Jonas Radžvilas. In 1925, In Šiauliai, he edited the futurists' newspaper and from 1931 to 1933 he editor of the literary department of the magazine , and from 1933 to 1941 the actual editor of the magazine. In 1928, Korsakas was arrested alongside some fellow students who were interested in Marxism and was held in the . A group of their friends requested amnesty from the president
Antanas Smetona by starting a petition which ended up successful. Korsakas was expelled from the
Lithuanian Komsomol after receiving the amnesty. He continued his literary activities by becoming a co founder of the left-wing
Trečias frontas magazine and a contributor to the magazine ''''. From 1931 to 1936 he attended literary courses at the
Vytautas Magnus University in Kaunas. During this period he contributed to multiple Lithuanian cultural and literary magazines. With the
Soviet occupation of Lithuania, he was appointed chairman of the . After the beginning of the
German invasion of the Soviet Union, Korsakas settled in Moscow and became chairman of the
Lithuanian Union of Writers and was an editor of the
Pergalė magazine. Korsakas was a deputy (1947–1963) and then Deputy Chairman (1959–1963) of the
Supreme Soviet of the Lithuanian SSR. He was buried in
Antakalnis cemetery. One street in the city of Šiauliai was named after him. == Literary works ==