Heavy alcohol use among people living with HIV in sub-Saharan Africa can hinder the success of HIV treatment programmes, impacting progress towards United Nations Programme on HIV/AIDS goals. Primary partners can provide critical forms of social support to reduce heavy drinking and could be included in motivational interviewing (MI) interventions to address heavy drinking; however, few studies have evaluated MI interventions for couples living with HIV in sub-Saharan Africa. We aim to evaluate the feasibility and acceptability of a couple-based MI intervention with mobile breathalyser technology to reduce heavy alcohol use and improve HIV treatment outcomes among HIV-affected couples in South Africa.