OBJECTIVES: This study investigated associations between recent maternal intimate partner violence (IPV) (emotional, physical and sexual) and child development at 2 years as well as whether maternal depression or alcohol use mediated these relationships. DESIGN: Cross-sectional study nested in a South African birth cohort. SETTING: Two primary care clinics in Paarl, South Africa. PARTICIPANTS: 626 mother-child pairs; inclusion criteria for maternal antenatal enrolment were clinic attendance and remaining in the study area for at least 1 year; women were excluded if a minor. PRIMARY OUTCOME MEASURES: Child cognitive, language and motor development composite scores. These were assessed using the Bayley Scales of Infant and Toddler Development, third edition. RESULTS: Emotional IPV was associated with lower cognitive (β=-0.32; 95% CI -0.60 to -0.04), language (β=-0.36; 95% CI -0.69 to -0.01) or motor composite scores (β=-0.58; 95% CI -0.95 to -0.20) in children at 2 years of age. Physical IPV was associated with lower motor scores (β=-0.42; 95% CI -0.75 to -0.09) at 2 years. Sexual IPV was unrelated to developmental outcomes, possibly due to low prevalence. Neither recent maternal depression nor alcohol use were shown to mediate the relationship between IPV and developmental outcomes. CONCLUSIONS: Interventions to reduce maternal physical and emotional IPV and early-life interventions for infants and toddlers are needed to promote optimal child development.