<p>The cognitive and behavioral development of left-behind children has aroused considerable attention, and family relationships have been regarded as important protective resources in the prior literature. However, despite its significance within the family system, intergenerational bonding has been overlooked in empirical studies regarding its impacts and pathways on left-behind children’s outcomes. This study aims to unpack the chain mechanisms behind left-behind children’s cognitive and behavioral competencies from the perspectives of intergenerational solidarity and psychological resilience. A total of 957 left-behind children aged 7–‍14 years old (<i>M =</i> 10.22, <i>SD =</i> 1.20) were recruited from three provinces in rural China. Results show that two major types of intergenerational bonding, parental bonding and grandparental bonding, were positively associated with cognitive-behavioral competencies. Grandparental bonding and resilience serially mediated the associations between parental bonding and cognitive-behavioral competencies. The findings, which align with intergenerational solidarity theory, expand the body of knowledge on how the three-generational dynamics of family relationships shape children’s development and elucidate the theory’s applicability in studying left-behind children. Practitioners may benefit from the findings to promote child well-being and competence via targeting intergenerational family dynamics and developmental resilience.</p>