Abstract Service quality is important to social workers and service recipients. However, limited research has explored the relationship between interference between work and family and service quality among social workers. According to conservation of resources theory, this study investigated how interference between work and family affects social workers’ service quality through emotional exhaustion and the moderating role of work support. The hypotheses were examined using data from 1,417 Chinese social workers collected during the China Social Work Longitudinal Study in 2019. The methodological design of this study includes hierarchical regression analysis and moderated mediation analysis. The results reveal that interference between work and family domains negatively affected service quality through emotional exhaustion as a mediating factor, whereas work support mitigated the direct (indirect) effects of work–family interference on emotional exhaustion (service quality through emotional exhaustion). This study presents a holistic understanding of how and when interference between family and work influences service quality. The findings encourage social work organisations to develop appropriate interventions targeting work–family conflict and emotional exhaustion to improve service quality.