Jan Willem Bertens was born on 23 January 1936 in Maastricht, Netherlands. He studied history at the Catholic University of Nijmegen, where he graduated in 1963, and he worked as a teacher of history. In 1966 he joined the Ministry of Foreign Affairs, where he worked in the diplomatic service in Uruguay, Sudan and Cuba. From 1977 to 1982 he was spokesman for the ministry.
Between 1989 and 1999 he was member of the European Parliament. During this period his was ally of the Liberal and Democratic Reformist Group, member of the Group of the European Liberal, Democrat and Reform Party and member of the Bureau of the Group of the European Liberal, Democrat and Reform Party. He was Chair of the Subcommittee on Security and Disarmament, Vice-Chair of the Subcommittee on Human Rights, member of the Committee on the Environment, Public Health and Consumer Protection, member of the Committee on Youth, Culture, Education, the Media and Sport, he was among the Members from the European Parliament to the Joint Assembly of the Agreement between the African, Caribbean and Pacific States and the EEC (ACP-EEC), he was member of the Committee on Foreign Affairs and Security, member of the Committee on Petitions, member of the Committee on Foreign Affairs, Security and Defense Policy, member of the Subcommittee on Security and Disarmament, member of the Subcommittee on Human Rights, member of the Delegation for relations with the countries of Central America and Mexico.