[3] Willem's father, Harm Buiter, was a Dutch economist, international trades union official and politician of the Labour Party (PvdA), who had served as Mayor of Groningen.

Buiter was awarded his PhD in economics from Yale University in New Haven, Connecticut, United States, in 1975.

In June 2000, he became Chief Economist and Special Advisor to the President at the European Bank for Reconstruction and Development, a position he held until August 2005.

[9] In April 2008, he wrote a paper about the situation of Icelandic banks for Landsbanki, together with his wife Anne Sibert.

In January 2010, Buiter joined Citigroup as Chief Economist, replacing Lewis Alexander who vacated the position to work with the United States Treasury eight months prior.

In an April 2009 blog post, Buiter had earlier described Citigroup as "a conglomeration of worst practice from across the financial spectrum.

Buiter, since 5 June 1998[1] is married to Anne Sibert, professor of economics at Birkbeck, University of London, who was also an External Member of the Monetary Policy Committee of the Central Bank of Iceland from 2009 until 2012.

Sibert, on account of her criticism on the banking system and European finances for the Centre for Economic Policy Research,[16] has been called "a commentator who cannot easily be ignored.