Polychronicity refers to the preference of some individuals to structure their time in order to deal with multiple tasks simultaneously in a short period of time. Past research regarding the correlation between individual polychronicity and performance presented distinct arguments. Although most studies supported a positive correlation with performance, empirical findings showed inconsistent results, indicating the presence of other influencing factors. According to the person–environment fit theory and self-determination theory, the effect of polychronicity on job performance was verified and the mediation effect of well-being was tested in this study. Dual-mode questionnaires were collected from 532 subordinators and their direct supervisors in 98 chain restaurants and hierarchical regression analysis was performed to test the research hypotheses. The results showed that polychronicity positively affected well-being, that is, well-being was a full mediator between polychronicity and job performance. This study provides valuable insight for managers to understand employee polychronicity and, in turn, improve their well-being, which could help improve job performance.