BACKGROUND: The combination of poverty, HIV and depression in the perinatal period represents a major public health challenge in many Southern African countries. In some areas, up to a third of HIV-positive women experience perinatal depression. Perinatal depression is associated with negative effects on parenting and key domains of child development including cognitive, behavioural and growth, especially in socio-economically disadvantaged communities. Several studies have documented the benefits of psychological interventions for perinatal depression in low- and middle-income countries, but none have evaluated an integrated psychological and parenting intervention for HIV-positive women using task-sharing. This randomised controlled trial aims to evaluate the effect of a home-based intervention, combining a psychological treatment for depression and a parenting programme for perinatally depressed HIV-positive women. METHODS: This study is a cluster randomised controlled trial, consisting of 48-60 geospatial clusters. A total of 528 pregnant HIV-positive women aged >/= 16 years who meet the criteria for depression on the Edinburgh Postnatal Depression Scale (EPDS, score >/= 9)) are recruited from antenatal clinics in rural KwaZulu-Natal, South Africa. The geospatial clusters are randomised on an allocation ratio of 1:1 to either the intervention or Enhanced Standard of Care (ESoC). The intervention group receives 10 home-based counselling sessions by a lay counsellor (4 antenatal and 6 postnatal sessions) and a booster session at 16 months. The intervention combines behavioural activation for depression with a parenting programme, adapted from the UNICEF/WHO Care for Child Development programme. The ESoC group receives two antenatal and two postnatal counselling support and advice telephone calls. In addition, measures have been taken to enhance the routine standard of care. The co-primary outcomes are child cognitive development at 24 months assessed on the cognitive subscale of the Bayley Scales of Infant Development-Third Edition and maternal depression at 12 months measured by the EPDS. ANALYSIS: The primary analysis will be a modified intention-to-treat analysis. The primary outcomes will be analysed using mixed-effects linear regression. DISCUSSION: If this treatment is successful, policymakers could use this model of mental healthcare delivered by lay counsellors within HIV treatment programmes to provide more comprehensive services for families affected by HIV. TRIAL REGISTRATION: ISRCTN registry # 11284870 (14/11/2017) and SANCTR DOH-27-102020-9097 (17/11/2017).