Monica Mayhem was born in 1978 and raised in Brisbane, Queensland, Australia. She is half Australian and half Welsh. She attended Kenmore State High School but was expelled and moved to Sydney alone when she was 16 to pursue a career in modeling and acting. She ended up in the world of finance instead and before long she was involved in the foreign exchange and futures trading markets. She left Australia to travel around Europe, then moved to London, where she worked in the IPE brokerage division of the renowned firm of Salomon-Smith-Barney. Tired of the dry and boring financial world, she was looking for a little excitement when she ran across an ad for "glamor" models. She wound up doing some softcore photo shoots in London and then decided to try exotic dancing and managed to land a gig at the world-famous Spearmint Rhino club in London.

In December 2000 she spontaneously decided to leave London and jumped on a plane to the US (allegedly on a dare) to begin acting in pornographic films. In 2002, she won the XRCO Award for Starlet of the Year and the FOXE Award for "Vixen of the Year". In August 2010, she announced that she had retired from pornographic acting, after over 400 films, and that she was engaged to a Sydney veterinarian.