Mark Donaldson was born in Newcastle, New South Wales, and later accompanied his family to Dorrigo. After a number of jobs in Australia and overseas, he joined the Australian Regular Army in 2002. In 2004 he was posted to the Special Air Service (SAS). At the time of his Victoria Cross action, 2 September 2008, he was on his second operational tour in Afghanistan.
Donaldson was returning to base in the Oruzgan province, in a joint US, Australian, and Afghan convoy when the group was ambushed. In heavy fighting, he moved from cover to cover to engage the enemy with anti-armour weapons as well as his own rifle, several times drawing the enemy's fire away from the wounded. He also rescued a wounded interpreter. His actions were described as being of the "highest accord and in keeping with the finest traditions of ... the Australian Defence Force". In 2010 he was appointed the National Australia Day Council's Young Australian of the Year.
Donaldson was awarded the Victoria Cross, the Australian Active Service Medal, the Afghanistan Campaign Medal, the Australian Defence Medal, and the NATO Medal.