Parental mentalization, as the ability to understand mental states (e.g., desires) behind their children’s actions, may play a relevant role in the prevention of future externalizing problems. We conducted a meta-analysis to examine the relationship between parental mentalization and children’s externalizing problems. Six electronic databases were searched for studies, published in English or Spanish, linking empirically those two variables. Participants included caregivers and children between 0 and 18 years. The filtering process yielded 42 studies with 52 effect sizes. Random-effect analysis revealed higher parental mentalization associated with fewer externalizing problems, with an effect size of r = −.19 (95% CI [−.25, −.13]). Due to high heterogeneity (I2 = 83.750), further analyses were conducted to explore factors affecting such association. Parenting experience and children’s developmental stage moderated the relationship, but approaches to operationalize mentalization (MM or PRF), sample type (clinical/at-risk vs. community), and reporting figure (primary caregiver vs. other informants) did not. The study highlights the significance of parental mentalization as a potential contributor to the prevention of externalizing behaviors among infants, children, and adolescents. Our findings may underscore practical implications for equipping caregivers with mentalization skills, helping them to answer appropriately to their children needs.