Mark O'Connor was born and educated in Melbourne, graduating from the University of Melbourne in 1965 with first-class honours in English and Classics. After teaching English at the University of Western Australia and the Australian National University, he took up writing full-time, winning several awards for his poetry in the early 1970s. He has collected many prizes since, including the FAW John Shaw Neilson Poetry Award (1981) and the Grace Perry Prize (1988). In the late 1970s O'Connor travelled in Europe on a Marten Bequest Travelling Scholarship. Soon after returning to Australia, he took up an appointment as writer-in-residence at James Cook University in North Queensland, the first of many similar appointments at various institutions. In 1988 he was the Museum of Victoria's Thomas Ramsay Science and Humanities Scholar.
O'Connor is one of Australia's best-known environmental poets. His first book of poetry was inspired by the Great Barrier Reef and he was later commissioned to write poetry about the high country for the New South Wales National Parks Service. O'Connor has received numerous grants and fellowships to support his writing, including a two-year Australia Council grant to serve as Sydney's 'Olympic Poet' and continue writing poetry about regional Australia. In 1998 O'Connor published This Tired Brown Land in which he argues that 'discussion of population and immigration issues has been stifled by ideology and vested interests' (Australianpoet.com website). Mark O'Connor continues to reside in Canberra and travels widely, reading his poetry and delivering lectures.