Perinatal mental health problems, particularly depression, are prevalent and have been a central focus of prevention initiatives. The greater proportion of ongoing annual perinatal mental health economic cost burdens relate to children. A key linking mechanism is mother-infant relationship quality. Perinatal depression symptoms are typically transient. However, personality style, including interpersonal sensitivity, is a more stable construct and predicts proneness to depression and common mental disorders. Building on our previous work, the objective of the present study is to examine the association between specific dimensions of prenatal interpersonal sensitivity and postpartum mother-infant relationship quality in the context of prenatal depression symptoms. We analysed data from the Avon Longitudinal Study of Parents and Children (ALSPAC). Interpersonal sensitivity and depression symptoms were measured at 18 weeks gestation. In a randomly selected 10% subsample of the ALSPAC cohort, mother-infant interaction was measured through standard observation at 12 months postpartum. For the subsample that had complete data at all time points (n = 812), multiple regression models examined prenatal interpersonal sensitivity dimensions predicting postpartum mother-infant relationship quality, accounting for depression symptoms. Two dimensions of maternal interpersonal sensitivity modestly predicted mother-infant relationship quality at 12 months postpartum and remained robust when we controlled for depression symptoms. The interpersonal sensitivity subscales were significantly associated with prenatal depression symptoms but more consistently and robustly predicted postnatal mother-infant interaction quality. The inclusion of personality measures may strengthen prenatal mental health assessment to identify vulnerability to suboptimal mother-infant relationship quality.