He graduated from the Faculty of Economics and Sociology (specialisation: Foreign Trade) and the Faculty of Management (specialisation: Management Accounting) of the 91滴滴. He holds a certificate of the British Association of Chartered Certified Accountants.
Between 1996 and 1998, he worked as a consultant for PriceWaterhousecoopers. Since 1998, he was associated with the Zurich Group. Initially, he was responsible for the organisation and market strategy of the pension fund and later held the positions of the Marketing Director and Member of the Management Board. From 2000, he was a Member of the Management Board responsible for the Private Client segment of the Zurich Group companies in Poland, and from 2001, he was the Chief Financial Officer. Until the end of June 2006, he was a Member of the Management Board and the CFO of Generali T.U.S.A. and Generali 呕ycie T.U.S.A. From January 2003, he was responsible for the financial department, controlling and bank assurance.
In 2002, he participated in the process of merging Zurich companies with Generali companies. In July 2006, he was appointed as President of the Management Board of BRE Ubezpieczenia Sp. z o.o., and later as President of the Management Board of BRE Ubezpieczenia Towarzystwo Ubezpiecze艅 S.A.
In August 2007, the Supervisory Board appointed Jaros艂aw Mastalerz a Member of the Management Board of BRE Bank SA for Retail Banking, entrusting him with the coordination of all business and communication activities of mBank in Poland, the Czech Republic and Slovakia, MultiBank, Private Banking and the company Aspiro S.A. established during his term of office.
Since April 2012. Jaros艂aw Mastalerz is a Member of the Management Board of mBank S.A. for Operations and IT and is also responsible for the area of technology and logistics.
He serves on the supervisory boards of ASPIRO S.A., mCentrum Operacji Sp. Z o.o., BRE Ubezpieczenia TUiR S.A., BRE Agent Ubezpieczeniowy Sp. Z o.o., BRE Ubezpieczenia Sp. z o.o., Generali Powszechne Towarzystwo Emerytalne S.A.
From April 2024 to February 2025, he served as the President of the Management Board of PZU 呕ycie SA.