Parenting stress and child psychopathology are closely linked in parent-child dyads, but how the bidirectional association varies across childhood and adolescence, and shifts depending on maternal affection are not well understood. Guided by the transactional model of development, this longitudinal, prospective study examined the bidirectional relations between parenting stress and child internalizing and externalizing problems and investigated the moderating role of maternal affection from childhood to adolescence. Participants were from the Future of Families and Child Wellbeing Study, a diverse, nationally representative sample of 2,143 caregiving mothers who completed assessments at children ages 5, 9, and 15. Using cross-lagged panel modeling, we found bidirectional effects between parenting stress and child internalizing and externalizing problems. However, additional multigroup analyses showed that bidirectional associations depend on the levels of maternal affection. In the high maternal affection group, parenting stress at age 5 predicted higher internalizing and externalizing problems at age 9, and reverse child-to-parent paths were found from age 9 to age 15. In contrast, only one cross-lagged path was found in the low maternal affection group. Findings suggest that maternal affection can heighten the transactional associations between parenting stress and child psychopathology.