Abstract Background The massive scale-up of antiretroviral treatment (ART) access worldwide has brought tremendous benefit to populations affected by HIV/AIDS. Optimising HIV care in countries with diverse medical systems is critical; however data on best practices for HIV healthcare delivery in resource-constrained settings are limited. This study aimed to understand patient characteristics and treatment outcomes from different HIV healthcare settings in Bangalore, India. Methods Participants from public, private and public-private HIV healthcare settings were recruited between 2007 and 2009 and were administered structured interviews by trained staff. Self-reported adherence was measured using the visual analogue scale to capture adherence over the past month, and a history of treatment interruptions (defined as having missed medications for more than 48 hours in the past three months). In addition, CD4 count and viral load (VL) were measured; genotyping for drug resistance-associated mutations was performed on those who were in virological failure (VL > 1000 copies/ml). Results A total of 471 individuals were included in the analysis (263 from the public facility, 149 from the public-private facility and 59 from the private center). Private facility patients were more likely to be male, with higher education levels and incomes. More participants reported ≥ 95% adherence among public and public-private groups compared to private participants (public 97%; private 88%; public-private 93%, p < 0.05). Treatment interruptions were lowest among public participants (1%, 10%, 5% respectively, p < 0.001). Although longer clinic waiting times were experienced by more public participants (48%, compared to private 27%, public-private 19%, p < 0.001), adherence barriers were highest among private (31%) compared with public (10%) and public-private (17%, p < 0.001) participants. Viral load was detectable in 13% public, 22% private and 9% public-private participants (p < 0.05) suggesting fewer treatment failures among public and public-private settings. Drug resistance mutations were found more frequently among private facility patients (20%) compared to those from the public (9%) or public-private facility (8%, p < 0.05). Conclusions Adherence and treatment success was significantly higher among patients from public and public-private settings compared with patients from private facilities. These results suggest a possible benefit of the standardized care delivery system established in public and public-private health facilities where counselling by a multi-disciplinary team of workers is integral to provision of ART. Strengthening and increasing public-private partnerships can enhance the success of national ART programs.