ObjectivesTo investigate how post-traumatic growth (PTG) and moral sensitivity influence service behaviour among healthcare workers (HCWs) in mainland China post-COVID-19, with a focus on the mediating role of moral sensitivity.DesignCross- sectional survey design.SettingThis study was conducted in 27 provinces across mainland China, from 16 March to 2 April 2023.Participants1,193 HCWs, including 378 physicians and 815 nurses, were selected using convenience and snowball sampling methods.MethodsThe survey included the Post-traumatic Growth Inventory-Chinese version (PTGI-C), the Moral Sensitivity Questionnaire-Revised Chinese Version (MSQ-R-CV) and a service behaviour scale. Structural equation modelling was employed to analyse the data, focusing on the associations between PTG, moral sensitivity, and service behaviours.ResultsThe study found significant associations between PTG and moral sensitivity (r=0.49, p<0.01), with both factors positively influencing HCWs’ service behaviours. Specifically, PTG had a direct effect on service behaviours (β=0.172, p<0.01) and an indirect effect through moral sensitivity (β=0.333, p<0.01), with moral sensitivity mediating 65.8% of PTG’s impact on service behaviours. The model explained 56.0% of the variance in service behaviours, indicating a substantial influence of these psychological factors on professional conduct.ConclusionsThe findings highlight the significant role of PTG and moral sensitivity in shaping the service behaviours of HCWs in the aftermath of the COVID-19 pandemic. The study suggests that enhancing PTG and moral sensitivity through targeted interventions could improve HCWs’ service delivery and resilience, emphasising the importance of incorporating psychological and ethical training into healthcare practices to prepare for future public health crises.