The environmental crisis poses a critical issue for current and future generations, driving research to investigate the key factors and psychological characteristics that motivate individuals to engage in pro-environmental behaviours (PEBs) from an early age. In this context, intergenerational transmission—which refers to how parents influence their children’s behaviour—plays a crucial role in initiating and promoting eco-friendly practices. From a children-centred perspective, the current study focused on the intergenerational transmission of PEBs, addressing the moderating role of children’s moral judgment. This latter was evaluated considering general moral judgment (i.e., moral transgressions, social-conventional transgressions, and non-harmful personal choices) and domain-specific environmental moral judgment (i.e., harmful actions with no specific victim, harmful actions to animals, and harmful actions to plants/trees). This study was carried out with 229 triads of Italian children (Mage = 8.54 years; SDage = 1.46 years; rangeage 6–11 years, 130 girls and 99 boys), fathers (Mage = 45.73 years; SDage = 5.07 years; rangeage 29–64 years), and mothers (Mage = 42.56 years; SDage = 4.67 years; rangeage 28–57 years). Results revealed that only the moral evaluations on harmful actions directed at animals (B = 0.32, SE = 0.15, t = 2.18, CI 95% = [0.030, 0.612]) and those towards plants/trees (B = 0.19, SE = 0.08, t = 2.49, CI 95% = [0.369, 0.342]) moderated the association between parents’ PEBs and children’s PEBs, boosting the intergenerational transmission of PEBs. Overall, this research yielded novel evidence on the main factors affecting the intergenerational transmission of PEBs, suggesting moral judgment as a critical mechanism in nurturing pro-environmental practices in school-age children. Implications, limitations, and future research directions are discussed.