Austin O’Sullivan was born in a rural area of County Meath, and went to school in Dundalk from 1952 to 57. He completed a four-year science degree course in the old College of Science in Merrion St in 1961, majoring in Botany. He was Chairman of the University College Dublin Biological Society in its 50th anniversary year (1961).
He carried out in 1961-64 the first grassland survey of Ireland, leading to a PhD degree in grassland ecology. He has been employed by the Agricultural Institute, now Teagasc, as a Research Officer since 1964. He is currently working as curator and manager of the Irish agricultural museum at Johnstonwn Castle.