Christa Randzio-Plath studied law, sociology and journalism at the universities of Kiel, Bonn, Strasbourg and Amsterdam. Between 1970 and 1989 she worked as publisher and a as lawyer. From 1976 to 1978 she was deputy head of the Council of Europe cabinet.
Randzio-Plath joined the Social Democratic Party (SPD) of Germany in 1964. Between 1986 and 1989 she served as a member of the Hamburg Parliament. In 1989, Randzio-Plath was elected member of the European Parliament and remained an MEP until 2004. During that period she was member of the Socialist Group, member of the Group of the Party of European Socialists, Chair of the Subcommittee on Monetary Affairs, Chair of the Committee on Economic and Monetary Affairs, member of the Committee on External Economic Relations, member of the Delegation for relations with the Member States of ASEAN and the Republic of Korea (AIPO), member of the Committee on Women's Rights, member of the Committee on Economic and Monetary Affairs and Industrial Policy, member of the Subcommittee on Monetary Affairs, member of the Temporary committee on employment, member of the Conference of Committee Chairs, member of the Committee on Economic and Monetary Affairs.
In 2004, Randzio-Plath returned to professional work as an advocate. She became a professor at the University of Hamburg as well as at the College of Europe. Until 2010 she was also an advisor to the European Commission.