Drawing from job demands–resources theory (Demerouti et al., 2001), this article investigates the effect of psychological flexibility, relative to surface and deep acting, in the relationship between day-level emotional demands and exhaustion. A total of 170 not-for-profit service workers first filled in a questionnaire and then completed a diary survey over three consecutive workdays. The results of multilevel analyses suggest that person-level psychological flexibility was associated with lower levels of daily emotional exhaustion (measured at bedtime). Moreover, person-level psychological flexibility was found to attenuate, whereas person-level surface acting was found to strengthen, the association between day-level emotional demands and day-level exhaustion. Person-level deep acting had no significant effect on daily exhaustion. These findings extend previous research by demonstrating the role of psychological flexibility in encouraging employees to handle their emotions primarily by accepting them rather than actively regulating (i.e. suppressing or changing) them.