He studied politics at the Queen's University of Belfast and later did a part-time postgraduate course in Public Policy Management with the University of Ulster at Magee
(
). While at QUB Durkan served as Deputy President of Queen's Students' Union from 1982-1983. He was also elected Deputy President of the Union of Students in Ireland from 1982-1984.
In 1990 Durkan became chairperson of the SDLP, a position he served in until 1995. He was a key member of the party's negotiating team in the run up to the Good Friday Agreement.
Following the Agreement Durkan was elected to the Northern Ireland Assembly in 1998, and became a member of the Northern Ireland Executive as Minister for Finance and Personnel.
He served in that position until 2001 when he replaced Seamus Mallon as deputy First Minister. He was also elected Leader of the SDLP in that year. Durkan was reelected to the Assembly in the election of November 2003. However, the Assembly and the Executive remain suspended.
In the 2005 general election he retained the Foyle seat at Westminster for the SDLP. While down on Hume's vote, Durkan won with a comfortable majority, despite a strong effort by Sinn Féin to take the seat. Durkan won 21,119 votes which was 46.3% of the total.
He is a Fellow of the British-American Project.