Background. Human immunodeficiency Virus is still a public threat and among the number one killer diseases across the world. The world made an effort to end these all burden through fast track by 2030 which are the three 90’s. Maximizing viral load suppression (VLS) is among the three 90’s. Viral suppression could be lower the risk of transmission of the virus to others and protect the health of infected individuals. Objectives. To assess viral load suppression and associated factors among HIV positive adults attending Hawassa University Comprehensive Specialized Hospitals, in Southern Ethiopia in 2019. Method and materials. Institutional based cross-sectional study design was conducted on 367 HIV positive adult on antiretroviral therapy (ART) for at least 2 months in Hawassa University Comprehensive Specialized Hospital, Hawassa. Data collection included a structured questioner and reviewing recorded data of viral load suppression (VLS). Binary and multivariable analysis used to assess magnitude of viral load suppression and associated factors of viral suppression. Result. Nighty eight percent response rate with a mean age of 34.6 and 63% female were participated in the study. The magnitude of viral suppression below 1000copies/ml was 78.5%. Multivariable analysis revealed that poor adherence [AOR=8.24 (95% CI=4.077-16.65)], BMI less than 17.5[AOR=4.366 (95% CI=2.307-8.25)], OIs [AOR=2.83 (95% CI=1.141-4.567)] and spent less time on HAART [AOR=2.097 (95% CI=1.064-4.137)] were associated to viral non suppression. Conclusion. Viral suppression of the Hospital was low as a goal of federal ministry of health and UNAIDs which is 90% of viral suppression. The Hospital should work on ART adherence, preventing OIs, supporting poor patients working with different stakeholders.