The success of a knowledge management system (KMS) depends on knowledge sharing. Numerous scholars and practitioners claim that motivational factors can facilitate successful knowledge sharing behavior. However, little empirical research has been conducted examining the different kinds of motivation (i.e., KMS empowerment) used to explain knowledge sharing behavior. By integrating a psychological empowerment perspective with the job characteristics theory (job significance, job autonomy, and task feedback), this study examines the role of KMS empowerment in explaining employee knowledge sharing behavior. Based on a survey of 183 employees from IT firms in Korea, this study applies the structural equation modelling approach to investigate the research model. The results show that KMS empowerment was significantly associated with knowledge sharing behavior, and work environment (job autonomy, task feedback, usefulness, and ease of use) enhanced KMS empowerment. However, job significance did not significantly influence KMS empowerment. The present findings’ implications for organizations are discussed.