From 1995 to 1999 she was a member of the European Commission responsible for Immigration, home affairs and justice; relations with the Ombudsman; and Financial Control and Fraud prevention.

Gradin was employed by the Social Affairs Planning Committee in Stockholm as secretary of the City College's Women's Affairs Committee, 1963–67, Secretary of State at the 1963 Council of Ministers, Member of the School Board's Educational Board 1971–81, by the International Health and Social Affairs Committee 1972–78, chairman of the Board of International Adoption Issues 1973–79 and Member of the 1982 Experts Group on Immigration Research.

She was responsible for immigration, justice and home affairs, relations with the European Ombudsman, economic governance and control and anti-fraud.

She ended up in focus since the anti-fraud campaign was found to be neglected and several Commissioners, in particular, Édith Cresson, were accused of corruption.

During her time in the EU Commission, Gradin contributed, among other things, to legislation on gender equality, increased transparency and criminalization of trafficking.