Johan Jacob Voskuil was a self-taught painter and illustrator. After working as a teacher in Breda, he settled in Bergen aan Zee in the 1920s, now fully devoting himself to the arts. As a communist, he illustrated many political flyers and book covers, including that of the 'Nieuwe Geïllustreerde Wereldgeschiedenis' (1929-32). Together with Cas Oorthuys he formed the advertising agency OV 20 between 1932 and 1935.
He was one of the comic artists who contributed to Dutch comic magazine De Humorist in 1941. He created a comic titled 'Klit, de Schoonzoon', about a tenacious son-in-law. Voskuil was part of the Amsterdam art group De Onafhankelijken, but ended his membership when the association joined the "Kulturkammer" of the nazi regime during World War II. During this period he contributed to the illegal magazine De Vrije Kunstenaar of sculptor and resistance man Gerrit van der Veen.
He was the second husband of German theater artist Dora Paulsen (1898 - 1970), whom he married in 1938. After the death of his wife and shortly before his own death, Voskuil remarried to opera singer Ruth Horna.