Baroness Nicholson of Winterbourne was ennobled and took her seat as a member of the House of Lords in the United Kingdom Parliament in 1997, having also served as a Member of the House of Commons and, subsequently, in the European Parliament.

She is a member of the United Kingdom Delegation to the Parliamentary Assembly of the Council of Europe where she sits on the Monitoring Committee.  She chairs the All-Party Parliamentary Groups for Foreign Affairs, and is the United Kingdom Trade Envoy to Iraq.

Outside her responsibilities as a member of the House of Lords, she is Executive Chairman of IBBC (Iraq Britain Business Council), Chairman of the AMAR International Charitable Foundation and Chairman of Asociatia Children’s High Level Group (Romanian) and a Chairman of the Supervisory Board of the Joint Leasing Company (Azerbaijan).

She is a member of the American Bar Association Middle East North Africa Council and a member of the Board of Trustees of the Global Warming Policy Foundation.

Baroness Nicholson was a Vice-Chairman of the Conservative Party (1983-1987), and joined the Liberal Democrats in December 1995. She contested the Blyth constituency in the 1979 General Election, and was a Member of Parliament for the Devon West and Torridge constituency (1987-1997). During that period she served as Parliamentary Private Secretary to the Minister of State at the Home Office, the Ministry of Agriculture, Fisheries and Food and at the Treasury. She was Liberal Democrat spokesperson for Overseas Development and Human Rights (1996-1997).

In 1999, she was elected to the European Parliament, representing the South East of England. During that period she was Vice-President of the Committee on Foreign Affairs, Human Rights, Common Defence & Security Policy; as Rapporteur for Iraq and Romania; as a Member of the Inter-Parliamentary Delegation to the Euro-Mediterranean Forum, the Stability Pact for South East Europe Parliamentary Group, and the Committee on Women’s Rights and Equal Opportunities.

From 2004, she served as a member of the Committee on Foreign Affairs (Vice-President 2004-2007), and the Sub-Committee on Human Rights. She was President of the first ever Permanent Delegation for Relations with Iraq, and a member of the Delegation for Relations with Iran. She was Rapporteur for Kashmir, for Romania (2004-2007). She served as Chief Observer to the European Union Election Observation Mission to Yemen in 2006, and as a member of the European Union Election Observation Missions to Palestine (2005), Azerbaijan (2005), Lebanon (2005 and 2009), Afghanistan (2005), Armenia (2007), and Pakistan (2008).

She is Vice-President of the Booker Prize Foundation, President of the Council of the Caine Prize for African Writing, President of the Booker Prize for Russian Fiction.