The workplace support, job burnout and income are powerful predictors of turnover intention, yet the potential mechanisms remain not fully understood amongst social workers in China. Framing the job demands-resources model, this study established a moderated mediation model to test the role of job burnout in mediating the association between workplace support and turnover intention, as well as the role of income in moderating the above mediating process. A survey was distributed to social workers from the China Social Work Longitudinal Study in 2019 to investigate their demographic information, Maslach’s Burnout Inventory, workplace support and turnover intention, and 4,704 respondents were included in the final analyses. The results showed that workplace support of social workers was negatively associated with turnover intention. Moderated mediation analyses revealed that monthly income buffered the negative association amongst the triad of workplace support, job burnout and turnover intention. The findings suggest that the government and social service agencies need to provide workplace support and offer a satisfying salary to reduce job burnout and turnover intention of social workers.