While business and psychology researchers have strived to identify effective strategies to reduce occupational stress, public administration scholars have paid insufficient attention to this issue. This article examines the role of motivational bases in the stressor–wellbeing relationship, a nascent research area in business and psychology, focusing on a particular type of motivation that is salient in public organizations: public service motivation (PSM). Based on a survey of 412 police officers from a large metropolitan city in eastern China, this study finds that PSM moderates the relationship between work stressors and individual wellbeing. Respondents with higher levels of PSM can better handle the increase of stressors so that their physical and mental wellbeing will decrease more slowly. Overall, respondents with higher levels of PSM tend to experience higher mental wellbeing but lower physical wellbeing than their low-PSM colleagues.