Longer exclusive breastfeeding duration has been associated with differences in neural development, better satiety responsiveness, and decreased risk for childhood obesity. Given hippocampus sensitivity to diet and potential role in the integration of satiety signals, hippocampus may play a role in these relationships. We conducted a secondary analysis of 149, 7–11‐year‐olds (73 males) who participated in one of five studies that assessed neural responses to food cues. Hippocampal grey matter volume was extracted from structural scans using CAT12, weight status was assessed using age‐ and sex‐adjusted body mass index (%BMIp85), and parents reported exclusive breastfeeding duration and satiety responsiveness (Children's Eating Behaviour Questionnaire). Separate path models for left and right hippocampus tested: (1) the direct effect of exclusive breastfeeding on satiety responsiveness and its indirect effect through hippocampal grey matter volume; (2) the direct effect of hippocampal grey matter volume on %BMIp85 and its indirect effect through satiety responsiveness. %BMIp85 was adjusted for maternal education, yearly income, and premature birth while hippocampal grey matter volume was adjusted for total intercranial volume, age, and study from which data were extracted. Longer exclusive breastfeeding duration was associated with greater bilateral hippocampal grey matter volumes. In addition, better satiety responsiveness and greater left hippocampal grey matter volume were both associated with lower %BMIp85. However, hippocampal grey matter volumes were not associated with satiety responsiveness. Although no relationship was found between breastfeeding and child weight status, these results highlight the potential impact of exclusive breastfeeding duration on the hippocampal structure. Given that hippocampus is sensitive to diet, it may play a role in the associations between longer exclusive breastfeeding duration, better satiety responsiveness, and decreased risk for childhood obesity. Longer exclusive breastfeeding duration was associated with greater bilateral hippocampal grey matter volumes. While breastfeeding duration was not associated with child weight status, better satiety responsiveness and greater left hippocampal grey matter volume were both associated with lower weight status. These results highlight the potential impact of exclusive breastfeeding duration on the hippocampal structure. Key messages Longer exclusive breastfeeding was associated with greater bilateral hippocampal grey matter volume but not satiety responsiveness in children. While exclusive breastfeeding duration was not directly associated with weight status, better satiety responsiveness and greater left hippocampal grey matter volume were both associated with lower weight status in children. This study highlights the potential impact of exclusive breastfeeding on hippocampal structure, providing a possible mechanism in which breastfeeding may reduce the risk for excess childhood weight gain. Future studies need to determine the relative impact that complementary periods of breastfeeding may have on regional brain development and satiety responsiveness.