Harold Mitchell was born in Trafalgar, Victoria, one of four children. His father was a sawmiller who had to go wherever the work was. His mother left the marriage when he was 15. By the time Harold was 16, the single-parent family was living in Stawell, Victoria. He left school early and worked in the local sawmill for some months and then went to work for an advertising agency in Melbourne, a city he had only ever visited once. He studied part-time at RMIT.
He became a successful media buyer, founded his own company, and led the development of the media buying industry in Australia.
He has been the chairman or board member of various organisations including the Florey Institute of Neuroscience and Mental Health, the New York Philharmonic, the National Gallery of Australia, the Museum Board of Victoria, Opera Australia, CARE Australia, the Melbourne Symphony Orchestra, Tennis Australia, the Deakin Foundation, the Melbourne International Festival of Arts, and the Australia-Indonesia Centre.
He is a major promoter of Australia overseas, such as in bringing Australian Indigenous art to millions worldwide.
His autobiography Living Large appeared in 2009.
Harold Mitchell presented the 2003 Andrew Olle Media Lecture.
He appeared on the ABC television program "Q&A" on 28 June 2010.
In the Australia Day Honours of 2004 Harold Mitchell was made an Officer (AO) of the Order of Australia, "For service to the community, particularly as a benefactor and fundraiser in support of artistic and cultural endeavour, and to business through advertising and media interests".
In the Queen's Birthday Honours of 2010, he was appointed a Companion (AC) of the Order of Australia, then Australia's highest civilian honour, "For eminent service to the community through leadership and philanthropic endeavours in the fields of art, health and education and as a supporter of humanitarian aid in Timor-Leste and Indigenous communities".
- Australian of the Year; retrieved 17 August 2013
- Business 21C Archived 2014-05-19 at the Wayback Machine; Retrieved 17 August 2013
- Harold Mitchell, Living Large; Retrieved 17 August 2013
- Harold Mitchell Foundation; Retrieved 17 August 2013
- Smart Company; Retrieved 17 August 2013
- The Age, 4 May 2012; Retrieved 17 August 2013
- National Press Club, Address 1 September 2009 Archived 3 April 2015 at the Wayback Machine: Retrieved 17 August 2013
- It's an Honour: AO; Retrieved 17 August 2013
- It's an Honour: AC; Retrieved 17 August 2013