BackgroundThe associations among maternal depressive symptoms (MDS), mother–child interactions and early child development are poorly understood. This study aimed to explore the role of mother–child interactions on the associations between MDS and child development.MethodsA cross-sectional study with a multistage sampling method was conducted in rural areas of Central and Western China. MDS, child development outcomes (communication, gross motor function, fine motor function, problem solving and personal social skills) and mother–child interactions were assessed by The Edinburgh Postpartum Depression Scale, the Chinese version of the Ages and Stages Questionnaires and the Multiple Indicator Cluster Surveys, respectively. Regression-based statistical mediation and moderation were conducted using the PROCESS macro for SPSS.ResultsA total of 2,548 participants (mothers: 1,274; children: 1,274) were included in our analyses. MDS was negatively associated with child development outcomes and mother–child interactions partly mediated these associations. The proportion of the mediating effect of mother–child interactions was 7.7% for communication, 8.2% for gross motor, 10.3% for fine motor, 10.1% for problem-solving and 9.5% for personal social domains. In addition, the interaction effects of MDS and mother–child interactions on the communication domain were significant (β = 0.070, 95% CI 0.016, 0.124; p = 0.011). The associations between MDS and child communication abilities were weaker at the high level (simple slope = −0.019, t = − 0.458, p = 0.647) of mother–child interactions than at the mean level (simple slope = −0.089, t = − 3.190, p = 0.002) and the low level (simple slope = −0.158, t = − 4.231, p < 0.001). Similar moderating effects were not observed in the other child development outcomes.ConclusionOur results suggest the important role of mother–child interactions on the associations between MDS and early childhood development. Due to the cross-sectional design of this study, these associations require further investigation in prospective studies.