After graduating from Queen's University Belfast, Mary McAleese was called to the Northern Ireland Bar and practised mainly in criminal and family law.

In 1975 she was appointed Reid Professor of Criminal Law, Criminology and Penology in Trinity College Dublin, a position she held until 1979 when she joined RTÉ as a journalist and presenter.She returned to the Reid Professorship at Trinity in 1981, while still continuing part-time with RTÉ.

In 1987, Mary McAleese was appointed Director of the Institute of Professional Legal Studies which trains barristers and solicitors for the legal profession in Northern Ireland. In 1994, she was appointed a Pro-Vice Chancellor of Queen's University Belfast.

Among the other appointments she has held are

Director of Channel 4 Television

Director, Northern Ireland Electricity

Director, Royal Group of Hospitals Trust

Delegate to the 1995 White House Conference on Trade and Investment in Ireland and to the follow up Pittsburg Conference in 1996

Member of the Catholic Church delegation in 1996 to the North Commission on Contentious Parades

Member of the Catholic Church Episcopal Delegation to the New Ireland Forum in 1984

Founder member of the Irish Commission for Prisoners Overseas.
On 11 November, 1997, Mary McAleese was inaugurated as the eighth President of Ireland.