Janusz Lewandowski was born in 1951, in Lublin, Poland. In 1974, he earned a Master's degree in Economics and in 1984 he got his Phd in Economics, both from the University of Gdańsk.

From 1974 to 1984 he was Associate Professor of International Trade and Maritime Transport at the University of Gdańsk.
During 1991, he was Poland’s Minister of Privatisation, and from November 1991 to September 1993, he was a Member of Parliament as well as, from December 1991 to July 1992, Chairman of the Parliamentary Committee for Privatisation. From July 1992 to October 1993, he returned as Minister of Privatisation, and was nominated in October 1993 Chairman of The Board of Trustees from The Gdańsk Institute for Market Economics, a position he still currently holds.
From 1997 to 2001, he was Deputy Chairman of the Committee for State Treasury and Privatisation in the Polish Parliament and, from 2001 to 2004 he was Deputy Chairman of the European Integration Committee. From April 2003 to April 2004 he was an Observer in the European Parliament, and in May 2004 became a Member of the European Parliament.

From May 2004 to February 2010, while Member of the European Parliament, he held various functions within the Committee on on Budgets eg. Chairman from July 2004 to January 2007 and Vice-Chairman from January 2007 to July 2009.

In February 2010, he joined the European Commission as Commissioner for Financial Programming and Budget. As the Commissioner he is responsible for Multiannual Financial Framework and annual budgets of the EU, among other things.