Background Childhood Human Immunodeficiency Virus (HIV) infection occurs almost exclusively via mother to child transmission (MTCT) during pregnancy, birth, or through breastfeeding. Recent studies have shown that male involvement (MI) in antenatal care (ANC) and HIV testing, including couples voluntary counselling and testing (CVCT), increases the likelihood that women will adhere to prevention advice and comply with HIV treatment if required during their pregnancy; hence reducing the rates of MTCT of HIV. This realist review investigates how, why, when, and for whom MI in ANC works best to provide contextual advice on how MI in ANC can be best used for prevention of mother to child transmission (PMTCT) of HIV. Methods A realist review of existing evidence was conducted. Realist review seeks to explain how and why an intervention works, or does not work, in a given context. This was completed through the five stages of realist synthesis; Eliciting the program theory, search strategy, study selection criteria, data extraction, and data analysis and synthesis. Findings are presented as context-mechanism-outcome (CMO) configurations outlining the mechanisms that work in given contexts to give an outcome. Results Three CMO configurations were developed. These describe that 1) Couples in monogamous relationships have higher levels of trust, commitment and security leading to increased uptake of PMTCT programs together; 2) ANC spaces that make ‘male friendly’ adaptions promote normalisation of MI in PMTCT and are more welcoming, leading to increased willingness of male partners to participate in ANC; and 3) couples and communities with higher health literacy encourage increased informed decision making, ownership, and responsibility and thus increased participation in PMTCT of HIV. Conclusions The CMOs developed in this review give contextual advice on how one might improve ANC services to increase MI and help reduce MTCT of HIV. We propose that MI in ANC works best where couples are monogamous and trusting, where ANC spaces actively promote being a ‘male friendly space’ and where there are high levels of community education programs around MTCT.