Background Sociodemographic factors are linked to cognitive outcomes in children born very preterm (VPT; ≤30 weeks gestation). The influence of maternal intellectual ability, a heritable trait, is unknown. Also undetermined is the extent to which associations between maternal and child intellectual ability vary according to parenting behaviors that target cognitive stimulation in the home. Methods At age 5 years, 84 VPT and 38 demographically matched full‐term (FT) children underwent neurodevelopmental assessment. Children's intellectual ability was assessed using The Wechsler Preschool Primary Scale of Intelligence‐III, and language was assessed with the Clinical Evaluation of Language Fundamentals Preschool‐2. The Wechsler Test of Adult Reading estimated maternal intellectual ability. The StimQ‐Preschool questionnaire provided a measure of cognitive stimulation in the home. Linear mixed‐effects models examined independent effects and interactions between maternal intellectual ability and cognitive stimulation on children's outcomes. Results After covariate adjustment, maternal intellectual ability was associated with child intellectual (p < .001) and language (p = .002) abilities. Stronger associations were observed in FT mother–child dyads (B = .63, p = .04) than VPT dyads (B = .42, p = .01). Mothers of VPT children reported lower levels of Parental Involvement in Developmental Advance (p = .007) and Parental Verbal Responsiveness (p = .04). Group differences in Parental Involvement in Developmental Advance, but not Parental Verbal Responsivity, persisted after adjusting for social background (p = .03). There was no evidence of an interaction between maternal intellectual ability and Parental Involvement in Developmental Advance (p = .34). Instead, maternal intellectual ability (p < .001) and Parental Involvement in Developmental Advance (p = .05) independently predicted VPT children's outcomes. Conclusions Maternal intellectual ability is an important trait linked to VPT and FT children's intellectual and language outcomes. Prematurity increases variation in the heritability of intellectual ability and shifts children from the expected range based on maternal ability. Parental involvement in activities that help children master new skills may promote cognitive development in VPT children born to mothers of lower intellectual ability.