ENCOVID-19 played a significant role in the spread of telework worldwide, changing people’s lives and behaviour. The paper aims to identify how teleworking affected the sustainable behaviour of employees during the COVID-19 pandemic. The research design applies a multi-method approach, combining systematic and comparative scientific literature analysis and a semi-structured interview. The authors of the paper present the theoretical conceptual model, which illustrates links between teleworking during the COVID-19 pandemic and the sustainable behaviour of employees. The results of empirical research revealed that teleworking during the COVID-19 pandemic changed employee behaviour in economic, environmental and social dimensions. Positive changes were identified due to reduced commuting and shopping; decreased costs for transport, food, clothing, and beauty services; better access to healthy and nutritious food; better opportunities for professional development. On the contrary, costs for home energy and household waste increased. Adverse effects on employees’ physical and mental health have been identified due to teleworking and COVID-19. Despite the identified negative effects, employees would like to continue teleworking even after the pandemic. Keywords: teleworking, sustainable behaviour, COVID-19. [From the publication]