Background Acquired immunodeficiency syndrome (AIDS) remains a major global public health challenge despite substantial advances in combination antiretroviral therapy (cART). Understanding factors associated with mortality among people living with HIV/AIDS (PLWH) receiving cART is essential, particularly in settings such as Oman, where long-term epidemiological data remain limited. This study aimed to evaluate long-term survival and identify predictors of mortality among PLWH receiving cART in Oman over 32 years.Methods An ambidirectional cohort study was conducted using data from the HIV/AIDS registry at the national tertiary referral hospital, the Royal Hospital in Oman, covering the period from January 1992 to December 2024. A total of 549 adult PLWH receiving cART were included. Clinical and laboratory data were extracted from electronic medical records and analyzed using descriptive statistics, Kaplan-Meier survival analysis, and multivariable Cox proportional hazards regression.Results Out of 549 individuals diagnosed with HIV/AIDS in Oman, 99 deaths were recorded. Of these, 83 deaths were due to AIDS-related causes, while 16 were due to other reasons. The overall incidence rate of deaths was 1.5 per 1,000 person-months (95% CI: [1.21, 1.80]). In the adjusted Cox model, patients aged 18 to 27 (adjusted hazard ratio (AHR) = 0.37, 95% CI: [0.16, 0.84]) and those aged 28 to 37 (AHR = 0.31, 95% CI: [0.15, 0.63]) exhibited a significantly lower hazard of mortality compared to individuals aged 48 and older. Additionally, patients in WHO stage 1 (AHR = 0.23, 95% CI: [0.09, 0.58]), stage 2 (AHR = 0.23, 95% CI: [0.06, 0.86]), and stage 3 (AHR = 0.39, 95% CI: [0.23, 0.64]) faced a reduced mortality risk in comparison to those with severe symptoms or stage 4. Low hemoglobin levels (< 10 g/dL) were associated with increased mortality (AHR = 1.75, 95% CI: [1.09, 2.81]).Conclusion The overall mortality incidence rate was 1.5 per 1,000 person months. Younger age, earlier clinical stage at diagnosis, and normal hemoglobin levels were associated with improved survival among people living with HIV/AIDS receiving combination antiretroviral therapy in Oman. These findings emphasize the importance of early diagnosis, timely treatment initiation, and strengthened national HIV programs to reduce HIV/AIDS related mortality.