Lance Corporal MacKinney was born in Canberra, Australian Capital Territory in 1982. He joined the Army in 2002 and in the same year successfully completed his recruit training. In 2003 he successfully completed his infantry training prior to being posted to the 6th Battalion, The Royal Australian Regiment. This was his third deployment to the Middle East.
Lance Corporal MacKinney was qualified as a commander and driver of the Protected Mobility Vehicle, an Assault Pioneer and a Sniper.
Lance Corporal MacKinney was killed in action during an intense fire-fight with Taliban insurgents on the morning of 24 August (Afghanistan time).