Zygmunt Kostkiewicz, a highly experienced executive manager, has been involved in the insurance market since the start of his professional career. He graduated in History from the University of Warsaw and the École Nationale d'Assurances in Paris. He is an active participant in the work of Insurance Europe in Brussels – ECOFIN.

In the 1990s, he served as Vice-President of the Management Board at Towarzystwo Ubezpieczeń Wzajemnych and Polisa Życie. He then became President of the Management Board at Commercial Union PTE BPH CU WBK, where he managed Poland's largest pension fund. Subsequently, he was President of the Management Board of PZU S.A. and then a member of the Management Board of Generali. In 2010, he was appointed President of the Management Board of KUKE S.A., a position he held for the next two years while managing key areas of the company's operations. In 2016, he began working with PGNIG, serving twice as President of the Management Board of Polski Gaz TUW. 

Graduated from the University of Finance and Management with a degree in Business Economic Analysis and Managerial Accounting, and postgraduate studies in Occupational Health and Safety and Ergonomics. Completed a training course for mediators, organised by the National Commission of NSZZ "Solidarność". In 2003, having successfully completed the state examination procedure, he was qualified to be a member of supervisory boards in State Treasury companies.

With PWPW since 1994 (initially employed at the Treasury Printing House, merged with PWPW in 2004). From 2003 to 2004, member of the Supervisory Board of the Treasury Printing House. From 2006 to 2022, elected chairman of the Plant Commission of the NSZZ "Solidarność" in PWPW for four terms. From 2006 to 2010, member of the Board of the Mazovia Region of the NSZZ "Solidarność" Trade Union. For years involved in the social affairs of PWPW employees, e.g. as a member of the Occupational Health and Safety Committee and the Chairman of the Social Committee, and since 2006 as a member of the Employee Council.