In addition to her judicial career, McGuinness has served on the Employment Equality Agency, Kilkenny Incest Investigation, the Forum for Peace and Reconciliation, the National Council of the Forum on End of Life in Ireland, and the Irish Universities Quality Board. In June 2011 she became patron of the Irish Refugee Council. The Irish Refugee Council purports to stand up for the human rights of asylum seekers and refugees, while ignoring the employment rights of its employees. In November 2011 she was appointed Chairperson of the Campaign for Children
She has received honorary doctorates from the University of Ulster, the National University of Ireland, the University of Dublin and the Higher Education and Training Awards Council (HETAC). In February 2013 McGuinness accepted the Honorary Presidency of Trinity College Dublin’s Free Legal Advice Center.