Hypertension significantly increases the risk of heart, brain, and renal diseases and is one of the leading causes of death and disease worldwide. It is a major comorbidity among HIV-positive people. There have been limited attempts to detect hypertension and its related variables in patients receiving antiretroviral treatment, notably in Addis Ababa, Ethiopia. The current study intended to examine the incidence of hypertension and related variables among adults aged 18 and over living with HIV on ART at selected public referral hospitals in Addis Ababa, Ethiopia. A hospital-based cross-sectional study was conducted on 411 HIV-positive individuals aged 18 on ART at Alert and St. Peter's Specialized Hospitals. The research was conducted between December 15, 2021, and January 20, 2022, using an interviewer administered standardized questionnaire. Epi-Info version 7.0 was used to enter and code the collected data, which was subsequently exported to SPSS version 23.0. Bivariate and multivariate logistic regression models were used to identify associated variables. The prevalence of hypertension among people with HIV on ART was 37.5% (95% CI: 32.8-42.5). Age groups 35-50 years (AOR: 2.18; 95% CI: 1.13-4.21), alcohol consumption (AOR: 5.58; 95% CI: 2.92-10.65), no physical exercise (AOR: 2.35; 95% CI: 1.06-5.21), family history of hypertension (AOR: 4.39, 95% CI: 2.48-7.76), duration of ART (AOR: 3.13; 95% CI: 1.20-8.12), low CD4 count (AOR: 1.87; 95% CI: 1.04-3.37), and body mass index greater than or equal to 25 kg/m2 (AOR: 2.38; 95% CI: 1.33-4.25) were factors associated with hypertension among HIV patients on ART. According to this study, hypertension is prevalent in HIV-positive people. Factors related with hypertension in PLHIV include alcohol intake, lack of physical activity, age 35-50 years, family history of hypertension, ART duration, low CD4 count, and BMI ≥25kg/m2. As a result, health education on the significance of keeping a healthy lifestyle can be effective in preventing and treating hypertension in HIV patients.