Simon started his senior career with Central Coast Lightning before joining Central Coast Mariners in 2006. In 2012, Simon signed with K-League club Chunnam Dragons, however, his opportunities at the club were limited by persistent injuries. In 2013, Simon rejoined the Mariners. He moved to Sydney FC after being released by the Mariners in 2015, before again returning to the Mariners in 2018. Simon remains the Mariners' all-time leading goal scorer, as well as a 6-time Mariners’ Golden Boot winner, record holder for the most substitute appearances in Australian league history, and scorer of the latest goal recorded in an A-League regular season match.