Few evidence-based interventions to improve adherence to antiretroviral therapy have been adapted for use in Africa. We selected, culturally adapted and tested the feasibility of a cognitive-behavioural intervention for adherence and for delivery in a clinic setting in Harare, Zimbabwe. The intervention consisted of a single, 50-minute problem-solving cognitive-behavioural intervention session with four skill-based booster sessions, delivered by four lay adherence counsellors in the context of HIV care. Adaptation followed a theoretically driven approach to intervention adaptation, Assessment-Decision-Administration-Production-Topical Experts-Integration-Training-Testing (ADAPT-ITT), and included modifications to language, session length, tailoring content for delivery by lay counsellors and inclusion of culturally competent probes. The feasibility of the intervention was evaluated using a mixed-methods assessment, including ratings of provider fidelity of intervention delivery, and qualitative assessments of feasibility using individual semi-structured interviews with counsellors (n = 4) and patients (n = 15). The intervention was feasible and acceptable when administered to 42 patients and resulted in improved self-reported adherence in a subset of 15 patients who were followed up after 6 months. Next steps from this study include conducting a randomised control trial to evaluate the adapted intervention compared to standard of care in a larger sample over a long-term follow-up.