President of the Association of Polish Stage Artists and, since 2002, director of the Juliusz Osterwa Theatre in Gorzów Wielkopolski. He is an actor, director, political scientist, and journalist, as well as an experienced leader of cultural institutions. During his tenure as director, the theatre building underwent a thorough revitalization. In 2003, the Summer Stage was established, which enjoys enormous popularity among the region's residents. He also created the 21st Century Stage and significantly raised the standard and prestige of the Gorzów Theatre Meetings – the oldest cultural event in the city.
Earlier Jan Tomaszewicz He was associated with the Syrena Theatre in Warsaw and the Polish Theatre in Bydgoszcz. He also managed the Lubuski Theatre in Zielona Góra. He received numerous awards for his work, including e.g.Silver Medal for Merit to Culture Gloria Artis (2016) and the title of Honorary Citizen of the City of Gorzów Wielkopolski (2020).