Preschoolers' prosocial behaviours support healthy interpersonal relationships as a component of their social adjustment process. Although several studies have found links between parental marital characteristics and preschoolers' prosocial behaviours, these conclusions were divisive. Therefore, a meta-analysis was conducted to clarify the inconsistencies in the research on these relationships and to examine the moderating effects underlying these discrepancies. A total of 37 effect sizes were extracted from the 31 included articles, with 14,374 sample sizes. The meta-analysis revealed a low positive link between parental positive marital quality and prosocial behaviours of preschool children, as well as a low negative correlation between negative marital quality and such behaviours. Additionally, the study explores the moderating effects of factors such as children's age, gender, cultural background, informant type, study design, and publication year. Finally, the study limitations were discussed, along with the aspirations for theoretical contributions, future research, and implications for parenting practices.