Rosamund O'Brien attended various schools in Victoria as her father moved regularly with his work as a farm manager. She completed her schooling at Our Lady's Convent, Ringwood, in Melbourne in 1946. O'Brien studied shorthand and typing at RMIT before commencing work with British Commercial News. She then worked with the Women's Royal Australian Air Force and Ansett Airlines prior to spending time in the UK and travelling in Europe.
After returning to Australia and marrying, O'Brien moved to Clunes where she and her husband established the Ballarat & Central Gazette. The newspaper was later sold to the Ballarat Courier (which was to become the Ballarat News). O'Brien continued to write columns for the newspaper and also wrote books on local history.
O'Brien is the mother of Justin O'Brien (q.v.).
Source: Justin O'Brien, 'Social Justice Activist Writ Large', Age, 'Business Day', (27 August 2011): 39