This study aims to analyze the effect of work environment and organizational culture on organizational commitment, with job stress as a mediating variable at the BPJS Employment Regional Office of Northern Sumatra. The study was motivated by the relatively low level of organizational commitment, suboptimal work environment and organizational culture, and high employee job stress. This research employed a quantitative approach with an associative design. The population consisted of 75 employees from the BPJS Employment Regional Office of Northern Sumatra, Medan Utara Branch Office, and Binjai Branch Office. A saturated sampling technique was used, involving all members of the population as respondents. Data were collected through questionnaires and analyzed using Partial Least Squares-Structural Equation Modeling (PLS-SEM) with SmartPLS. The results show that organizational culture has a positive and significant effect on organizational commitment and a negative and significant effect on job stress. The work environment has a negative and significant effect on job stress but does not have a significant direct effect on organizational commitment. Job stress has a negative and significant effect on organizational commitment. Furthermore, job stress significantly mediates the effects of organizational culture and work environment on organizational commitment. These findings indicate that strengthening organizational commitment requires not only a strong organizational culture and a supportive work environment but also effective management of employee job stress.