The article addresses the issue of the management and functioning of biosphere reserves (BRs) in Poland. The hypothesis was raised that BRs in Poland are virtual rather than real entities. The study examined how the existence of BRs is reflected in Polish strategic and planning documents. The study examined documents from 1947 to 2022, i.e., Polish legal acts (archived and current), the national Strategy for Responsible Development, voivodeship strategies, and national park protection plans. It evaluated to what extent the biosphere reserves fulfil their role in Poland, as defined by the Man and Biosphere program. To verify the research questions, legal documents (laws and regulations) enacted by the Polish authorities, strategies, and planning documents created at the central and voivodeship levels, protection plans for nature conservation forms covering biosphere reserves, economic plans of entities managing biosphere reserves, and other documents were analyzed. It was shown that: (1) BRs do not have a legal basis in Polish legislation at the national level, despite Poland’s ratification of the Man and Biosphere program, (2) there is a lack of detailed information about BRs in national and voivodeship strategic documents (development strategies and spatial development plans for voivodeships), (3) the existence of biosphere reserves does not translate into spatial planning principles at the local level (municipalities), (4) there is no legal possibility to separate tasks related to biosphere reserves in nature conservation protection plans (national parks, nature reserves, and landscape parks), (5) in the case of transboundary BRs, the Inspection carried out in the Carpathians International Biosphere Reserve (Poland-Ukraine-Slovakia) showed only formal cooperation, not practical. In conclusion, the management of BRs and the implementation of tasks contained in the MaB program, particularly those related to sustainable development of the environment, society, and economy, are ineffective due to the lack of legal authorization in Poland.