AbstractThis study aimed to assess the association between suicidal ideation among mothers living with HIV in Zimbabwe and the cognitive development of their children. Participants were mother–child dyads recruited from two rural districts in Zimbabwe. Data were collected at baseline and 12 months follow-up. Suicidal ideation was assessed using item-10 from the Edinburgh postnatal depression scale. Mixed-effects linear regression was used to assess the association of child cognitive outcomes at follow-up (using the Mullen scales of early learning) with maternal suicidal ideation. Mothers with suicidal ideation at baseline (n = 171) tended to be younger, unmarried, experienced moderate to severe hunger, had elevated parental stress and depression symptoms compared with non-suicidal mothers (n = 391). At follow-up, emerging maternal suicidal ideation was associated with poorer child cognitive outcomes (adjusted mean difference − 6.1; 95% CI − 10.3 to − 1.8; p = 0.03). Suicidal ideation affects child cognitive development and should be addressed, particularly in HIV positive mothers.