On 26 January 1991, Mitchell was appointed a Companion of the Order of Australia (AC), Australia's highest civilian honour, for services to the law, to learning, and to the community. She was made a Commander of the Royal Victorian Order (CVO) on 1 January 2000. Mitchell was to receive her honour directly from The Queen of Australia, however, as her health deteriorated, the Governor-General, Sir William Deane, flew to Adelaide and attended her bedside to bestow the honour in a private investiture.