Terence Wynn in 1962, started to work in the merchant navy. He joined the Labour Party.
In 1989 Terence Wynn was elected member of the European Parliament and remained an MEP until 2006. During that time he was member of the Socialist Group, member of the Group of the Party of European Socialists, Chair of the Committee on Budgets, Vice-Chair of the Committee on Budgetary Control, Vice-Chair of the Delegation for relations with Australia and New Zealand, Vice-Chair of the Temporary committee on policy challenges and budgetary means of the enlarged Union 2007-2013, member of the Committee on Development and Cooperation, member of the Members from the European Parliament to the Joint Assembly of the Agreement between the African, Caribben and Pacific States and the EEC (ACP-EEC), member of the Committee on Budgets, member of the Committee on Budgetary Control, member of the Members from the European Parliament to the Joint Assembly of the Agreement between the African, Caribbean and Pacific States and the European Union (ACP-EU), member of the Delegation to the EU-Turkey Joint Parliamentary Committee, member of the Delegation for relations with Australia and New Zealand, member of the Conference of Committee Chairs and member of the Committee on Agriculture and Rural Development.