Parent-child dysfunctional interactions (PCDI) are known to contribute to children's weight status. However, the underlying mechanisms in how dysfunctional interactions between parent and child influence child weight are not clear. This study investigates the impact of PCDI on toddlers' weight, focusing on the potential serial mediation by maternal emotional feeding and child appetite traits. We conducted a secondary analysis of longitudinal data from a larger intervention trial to prevent childhood obesity in low-income Hispanic families. A total of 241 mother-child dyads were included in these analyses. Measurements were taken at various stages: PCDI at child age 19 months, maternal emotional feeding at 28 months, and both child appetite traits and weight-for-age z-score (WFAz) at 36 months. Serial mediation analyses revealed a significant indirect effect of early PCDI on later child WFAz through maternal emotional feeding and two child food approach traits (food responsiveness, emotional overeating) out of the eight child appetite traits assessed. PCDI at 19 months was associated with increased use of emotional feeding in mothers at 28 months, which was associated with heightened food responsiveness and emotional overeating in children at 36 months, which in turn was linked to greater child WFAz at 36 months. The findings of this study expand the understanding of the mechanisms underlying PCDI and child weight, emphasizing the interplay between maternal feeding practices and child appetite in the context of adverse parent-child interactions during early childhood.