Objectives <p>The present study tested the unique contributions of prenatal maternal mindfulness to infant emerging effortful control and negative affect at 6&#xa0;months postnatal. Exploratory analyses evaluated the role of individual facets of mindfulness in predicting infant outcomes.</p> Method <p>The sample consisted of 178 individuals. Participants completed self-report measures of mindfulness during pregnancy (<i>M</i> = 16.91 gestational weeks; <i>SD</i> = 4.37) and postnatally (<i>M</i> = 6.54&#xa0;months after birth; <i>SD</i> = 2.12). At 6&#xa0;months postpartum, participants also reported on their infants' (55% female) emerging effortful control and negative affect using the Infant Behavior Questionnaire.</p> Results <p>Greater prenatal maternal mindfulness was associated with higher infant emerging effortful control (<i>β</i> = 0.40, <i>p</i> &lt; 0.001) and lower negative affect (<i>β</i> = -0.16, <i>p</i> = 0.04). These relations remained statistically significant when controlling for postnatal mindfulness. The prenatal describing (<i>β</i> = 0.21, <i>p</i> = 0.02) and nonreacting (<i>β</i> = 0.28, <i>p</i> = 0.01) subscales of mindfulness were statistically significant predictors of emerging effortful control after controlling for postnatal mindfulness subscales. None of the subscales were significant predictors of infant negative affect after controlling for postnatal mindfulness.</p> Conclusions <p>Maternal prenatal mindfulness predicted both infant emerging effortful control and negative affect. Individual facets of prenatal mindfulness demonstrated unique patterns of association with infant emerging effortful control, suggesting that aspects of mindfulness may be promotive factors to consider in future interventions. These findings highlight that mindfulness during pregnancy is linked to improved infant self-regulation and reduced emotional reactivity.</p> Preregistration <p>This study is not preregistered.</p>