This study investigates the mechanisms and conditions through which coworker knowledge sharing influences employee creativity, grounded in the conservation of resources (COR) theory. Specifically, the study proposes that employee self-efficacy functions as a mediating mechanism in the relationship between coworker knowledge sharing and employee creativity, while job demands serve as a boundary condition for this indirect effect. To test these hypotheses, two studies were conducted in South Korea. Study 1 analyzed data from 198 supervisor-employee dyads within a state-owned enterprise, while Study 2 examined data from 241 dyads across six of the nation's largest private companies. Results indicate that coworker knowledge sharing significantly enhances employee creativity, with self-efficacy fully mediating this relationship. Furthermore, the findings reveal that job demands moderate both the effect of coworker knowledge sharing on employee self-efficacy and the indirect effect of coworker knowledge sharing on employee creativity via self-efficacy. The study discusses implications for both theory and practice.