BACKGROUND: Integration of health services might be an efficient strategy for managing multiple chronic conditions in sub-Saharan Africa, considering the scope of treatments and synergies in service delivery. Proven to promote compliance, integration may lead to increased economies-of-scale. However, evidence on the socio-economic consequences of integration for providers and patients is lacking. We assessed the clinical resource use, staff time, relative service efficiency and overall societal costs associated with integrating HIV, diabetes and hypertension services in single one-stop clinics where persons with one or more of these conditions were managed. METHODS: 2273 participants living with HIV infection, diabetes, or hypertension or combinations of these conditions were enrolled in 10 primary health facilities in Tanzania and Uganda and followed-up for up to 12 months. We collected data on resources used from all participants and on out-of-pocket costs in a sub-sample of 1531 participants, while a facility-level costing study was conducted at each facility. Health worker time per participant was assessed in a time-motion morbidity-stratified study among 228 participants. The mean health service cost per month and out-of-pocket costs per participant visit were calculated in 2020 US$ prices. Nested bootstrapping from these samples accounted for uncertainties. A data envelopment approach was used to benchmark the efficiency of the integrated services. Last, we estimated the budgetary consequences of integration, based on prevalence-based projections until 2025, for both country populations. RESULTS: Their average retention after 1 year service follow-up was 1911/2273 (84.1%). Five hundred and eighty-two of 2273 (25.6%) participants had two or all three chronic conditions and 1691/2273 (74.4%) had a single condition. During the study, 84/2239 (3.8%) participants acquired a second or third condition. The mean service costs per month of managing two conditions in a single participant were $39.11 (95% CI 33.99, 44.33), $32.18 (95% CI 30.35, 34.07) and $22.65 (95% CI 21.86, 23.43) for the combinations of HIV and diabetes and of HIV and hypertension, diabetes and hypertension, respectively. These costs were 34.4% (95% CI 17.9%, 41.9%) lower as compared to managing any two conditions separately in two different participants. The cost of managing an individual with all three conditions was 48.8% (95% CI 42.1%, 55.3%) lower as compared to managing these conditions separately. Out-of-pocket healthcare expenditure per participant per visit was $7.33 (95% CI 3.70, 15.86). This constituted 23.4% (95% CI 9.9, 54.3) of the total monthly service expenditure per patient and 11.7% (95% CI 7.3, 22.1) of their individual total household income. The integrated clinics' mean efficiency benchmark score was 0.86 (range 0.30-1.00) suggesting undercapacity that could serve more participants without compromising quality of care. The estimated budgetary consequences of managing multi-morbidity in these types of integrated clinics is likely to increase by 21.5% (range 19.2-23.4%) in the next 5 years, including substantial savings of 21.6% on the provision of integrated care for vulnerable patients with multi-morbidities. CONCLUSION: Integration of HIV services with diabetes and hypertension control reduces both health service and household costs, substantially. It is likely an efficient and equitable way to address the increasing burden of financially vulnerable households among Africa's ageing populations. Additional economic evidence is needed from longer-term larger-scale implementation studies to compare extended integrated care packages directly simultaneously with evidence on sustained clinical outcomes.