Background: World Health Organization (WHO) recommends that viral load ([VL) is a primary tool that clinicians and researchers have used to monitor patients on antiretroviral therapy (ART), an antiviral drug against retroviruses. Whereas, CD4 cell counts can only be used to monitor clinical response to ART in the absence of VL testing service. Therefore, this study is aimed to assess the level of immunological status and virological suppression, and identify associated factors among human immunodeficiency virus ([HIV)-infected adults who were taking antiretroviral drugs of combination regimen know as highly active antiretroviral therapy (HAART). Methods: A hospital-based cross-sectional study was conducted at the University of Gondar comprehensive specialized referral hospital from February to April 2018. A total of 323 adult participants on HAART were selected using a systematic random sampling technique and enrolled into the study. Blood samples for viral load determination and CD4 cell count were collected. Binary logistic regression analysis was used to determine factors associated with immunologic status and virological suppression in HIV patients on HAART. Odds ratio with 95% CI was used to measure the strength of association. Results: Virological suppression (VL level < 1000 copies/ml) was found in 82% (95% CI 77.7, 86.1) of study participants, and it has been associated with CD4 cell count between 350 and 499 cells/mm 3 (adjusted odds ratio (AOR) = 2.56; 95% CI 1.14, 5.75) and > 499 cells/mm 3 (AOR = 7.71; 95% CI 3.48, 17.09) at VL testing and current age > 45 years old (AOR = 5.99; 95% CI 2.12, 16.91). Similarly, favorable immunological status (≥ 400 cells/mm 3 for male and ≥ 466 cells/mm 3 for female) was observed in 52.9% (95% CI 47.4, 58.8) of the study participants. Baseline CD4 cell count of > 200 cells/mm 3 , age at enrollment of 26 through 40 years old, and urban residence were significantly associated with favorable immunological status. Conclusion: Though the majority of HIV-infected adults who were on HAART had shown viral suppression, the rate of suppression was sub-optimal according to the UNAIDS 90-90-90 target to help end the AIDS pandemic by 2020. Nonetheless, the rate of immunological recovery in the study cohort was low. Hence, early initiation of HAART should be strengthened to achieve good virological suppression and immunological recovery.