[3] Jan's grandfather was Jakub Rothfeld (who left Judaism, changed his surname to Rostowski and regarded himself as a Pole), a professor of neurology at the John Casimir University in Lwów.

In 1991, he co-founded the Warsaw-based Centre for Social and Economic Analysis (CASE), a think-tank designed to assist Europe’s newly independent nations during the transition to capitalism.

During his six-year tenure at the ministry, Rostowski oversaw an overhaul of the public finance sector, including a cap on spending growth and a decision to redeem sovereign bonds held by privately managed pension fund companies, a move that drew criticism from the fund companies and some economists.

[15] In late 2015, Prime Minister Ewa Kopacz appointed Rostowski as her top political adviser.

[16] In January 2025, he became acting head of the Permanent Representation of the Republic of Poland to the Organisation for Economic Co-operation and Development.

He is the author of academic books including Macroeconomic Instability in Post-Communist Countries published by Oxford University Press.

On social matters, he previously opposed in-vitro fertilisation, abortion and same-sex civil unions.