The rise of the Sustainable Development (SD) concept contributed to the increasing interest in practices encompassing the Sustainable Human Resource Management (Sustainable HRM) and the results of these practices. This article relates to the area of Human Resource Management and activities undertaken by HR departments to implement the principles of sustainable development in the enterprise. In particular, it refers to the concept of Sustainable HRM, recognized by many researchers as a new paradigm in the area of HRM. Although an intensely-studied subject, there is a clear gap in research regarding Sustainable HRM in Polish companies. Additionally, there is a lack of research contribution on the Podlasie region—ecologically and ethnically the most diverse region in the country. While sustainability in environmental terms is evident in the region, the article focuses on sustainability implementation in the business sector. The article helps to close the research gap. Its aim is to examine the two-fold role of HR departments in: Implementing activities in the area of Sustainable HRM, and introducing the principles of sustainability to corporate strategies. It was assumed that such activities contribute to corporate sustainability. In order to verify the role of HR departments, a new, comprehensive research model, based on the work of De Prins, was built. The model relates to the double-task of HR departments in organizations. The added value of the article stems from the research model proposal, which can be applied without geographical limitations and to numerous organization types. The paper introduces one of the applications of the model—a regional one. The model was tested in a questionnaire survey conducted among employees of enterprises operating in the Podlaskie Voivodeship, which is unique in terms of environment, culture, and economy in Poland. The respondents were participants of MBA studies at one of the universities of the Podlaskie Voivodeship. The results of the study fully confirmed the hypothesis adopted in the study regarding the performance of activities by HR departments in the psychological and social areas of Sustainable HRM. The third aspect of the study, regarding the ecological area, was not clearly confirmed in the study. It was found that this may result from the restrictive law regulating the issue of the impact of enterprises on the natural environment. The results of the study allowed for the verification of the main hypothesis assumed in the research model, thus confirming its truthfulness.