Background: Early and sustained viral suppression with antiretroviral therapy (ART) has been linked to good clinical outcome in HIV-infected patients. The global target is that at least 90% of the patients on ART should be virally suppressed. Objectives: We assessed the virologic response to first-line ART in the first year of treatment in our center and determined the factors influencing early viral load suppression among patients. Materials and Methods: We conducted a retrospective study involving review of the records of all eligible HIV-infected adults initiated on ART in our facility between 2009 and 2014, who did not miss any follow-up appointment during the first year on ART. Data were extracted with a proforma and analyzed with Epi Info 7. Frequencies and proportions were used to summarize patients who achieved undetectable viremia (viral load < 400 copies/mL]) at 12 and 24 weeks, whereas χ2 and logistic regression were done at 5% alpha to determine the factors influencing early viral load suppression. Results: The mean age of 478 participants was 38.6 (19.0) years and 310 (64.8%) were females. While 332 (69.5%) patients achieved undetectable viremia at 12 weeks of ART, 356 (74.5%) achieved it at 24weeks. After 24 weeks on ART, 121 (80.7%) of the150 patients on tenofovir/emtricitabine/efavirenz, 195 (71.2%) of the 274 patients on zidovudine/lamivudine/nevirapine, and 35 (71.4%) of the 49 patients on tenofovir/lamivudine+nevirapine achieved undetectable viremia (P = 0.13). Patients’ age, sex, marital status, baseline CD4 count, TB co-infection status, WHO clinical stage of disease, and plasma viral load at ART initiation were not significantly associated with early viral load suppression (p > 0.05). Conclusion: Three out of every four participants initiated on first-line ART achieved undetectable viremia after 24 weeks of treatment in our setting. The three ART regimens assessed have comparable effectiveness. The sociodemographic and clinical variables assessed did not influence viral suppression.