Joergen Mogensen's career as a cartoonist began in 1944, when he delivered his first drawings to the musician and cartoonist Cospers Hudibras. Together with Cosper, Joergen Mogensen later drew the pantomime series Alfredo under their joint pseudonym MOCO. Alfredo was featured in newspapers all over the world.

From 1946, he became associated with the danish magazine Politiken and their sunday magazine. This was were Poeten og Lillemor came to be in 1950 and it only ended the year before Jorgen Mogensen died.

Joergen Mogensen was married to the artist Gerda Nystad. They had three children.

Jørgen Mogensen har bl.a. udstillet på 'The Metropolitan Museum of Art, New York', og Kunstindustrimuseet og i 1987 blev han tildelt den danske tegneseriepris Ping for sin indsats.

Joergen Mogensen has, among other things, exhibited at 'The Metropolitan Museum of Art, New York', and the Design Museum Denmark, and in 1987 he was awarded the Danish comics prize Ping for his efforts.