Steven Horne, the son of an army sergeant-major, was born in Queensland and grew up in Sydney, near the Ingleburn army base. Horne trained as an army officer at the Royal Military College, Duntroon, and subsequently served as an interpreter with the Australian Army's peacekeeping force in East Timor. He has also worked as a private contractor with the British Army in Iraq and for a Swiss company providing logistics support for NATO forces in the Middle East and Europe.
