Economist by training. For most of his career associated with the Faculty of Economics and Sociology at University of Łódź. Participant of internships at Columbia University, University of Chicago and at London School of Economics. Twice served as Deputy Prime Minister and Minister of Finance: in 1997 in the government of Wlodzimierz Cimoszewicz's government and in 2001-2002 in Leszek Miller's government.
In 2004-2005, he was Prime Minister of the Government of the Republic of Poland.
Professor Belka has also held many positions in international institutions. In 2003-2004 he was head of the Coalition Council for International Coordination in Iraq (2003), and then director of economic policy at the Coalition Provisional Authority in Iraq. From 2006 to 2008, he served as Executive Secretary of the United Nations Economic Commission for Europe (UNECE), and, from November 2008, he was director of the European Department of the International Monetary Fund. On 10th of June 2010, he was appointed by the Sejm of the Republic of Poland as President of the National Bank of Poland for a six-year term of office.
Professor Belka was sworn in as a new Member of the European Parliament on the 2nd July 2019. (term 2019-2024). He was a member of the parliamentary Committee on Economic and Monetary Affairs, deputy member of the parliamentary Committee on International Trade, member of the Delegation for Relations with the USA and an alternate member in the Delegation for Relations with Central American Countries. In 2020, he was appointed to the Subcommittee on Fiscal Affairs in 2020.