Leon Carmen grew up in Torrens Park, Adelaide, and was educated at Unley High School. His father died when he was fourteen years old. He was a member of Red Angel Panic, an early South Australian rock band, and has worked as a public servant, a taxi-driver and a fruit-picker. He moved to Sydney in 1995.
With the help of his literary agent, John Bayley, Carmen wrote an 'autobiography' of a fictitious character, 'Wanda Koolmatrie'. This novel won the Nita May Dobbie Award for a first novel by a woman writer, before being exposed as a hoax in 1997.