Settling in Paris, he studied at the Faculty of Law at the Lyceum of Charlemagne, where he met Louis Delluc, who had a significant influence on Mussinac, attracting him to poetry, theater, interested in painting and modern literature.

It was because of him that the films of Dziga Vertov and Strike by Sergei Eisenstein were shown at the 1925 Exhibition of Decorative Arts.

[2][3] In 1930 along with Paul Vaillant-Couturier and Louis Aragon, Moussinac founded the Association des Écrivains et Artistes Révolutionnaires (AEAR) created in France, at the head of it which also appeared Charles Vildrac and Francis Jourdain.

After he was released he was forced to hide for a long time in the south of the country, wanted by the French police.

[1] Leon Mussinac died of a heart attack on 10 March 1964 and is buried in the Père Lachaise cemetery near the Wall of the Communards.