A study conducted in Shenzhen, China, examined the intergenerational co-parenting relationships between mothers and grandparents of infants and toddlers. Researchers aimed to identify different types of these relationships and how they relate to maternal psychological well-being. A survey of 366 mothers revealed three distinct co-parenting profiles: the Discordant Group (29.2%), the Balanced Group (46.7%), and the Harmonious Group (24.0%). Mothers in the Discordant Group experienced the highest levels of stress and depressive symptoms, while those in the Harmonious Group reported the best psychosocial outcomes. Factors contributing to a more harmonious relationship included higher spousal co-parenting scores, lower parenting stress, and better sleep quality. Interestingly, greater maternal parenting competence was associated with increased intergenerational conflict. The findings highlight the importance of fostering positive co-parenting dynamics among families to improve maternal mental health and family functioning during early childhood. Healthcare professionals, including nurses, are encouraged to develop family-based interventions tailored to these identified co-parenting profiles to better support mothers and enhance intergenerational cooperation in caregiving.