PURPOSEAIDS-related mortality declined markedly since the introduction of antiretroviral therapy (ART); however, cancer mortality in Africa was higher than its incidence in 2020. People living with HIV (PLWHIV) are at an increased risk of malignancy and death from malignancy compared with the general population. In Uganda, AIDS-defining malignancies (ADMs), including cervical cancer, Kaposi sarcoma, and non-Hodgkin lymphoma, are among the commonest malignancies. Virologic nonsuppression has been identified as an important predictor of mortality among PLWHIV diagnosed with cancer. This study aimed to determine the prevalence and to identify factors associated with virologic nonsuppression among PLWHIV newly diagnosed with cancer.METHODSThis was a cross-sectional study that was carried out between December 2018 and April 2019 at the Uganda Cancer Institute. PLWHIV who had been on ART for at least 6 months and were newly diagnosed with cancer were enrolled.RESULTSA total of 167 participants were enrolled. Cervical cancer was the commonest ADM (n = 45; 50.6%) of all ADMs, while esophageal and breast cancers were the commonest non-ADMs, accounting for 17.5% (n = 14) each of all non-ADMs. The prevalence of virologic nonsuppression was 15%. Having Kaposi sarcoma (odds ratio [OR], 8.15;P= .003), being poorly adherent to ART (OR, 4.1;P= .045), and being on second-line ART (OR, 5.68;P= .011) were associated with virologic nonsuppression.CONCLUSIONThe prevalence of virologic nonsuppression is high among patients with HIV newly diagnosed with cancer. These findings emphasize the need for strengthening of adherence strategies, optimizing ART regimens, and prioritization of viral load testing among PLWHIV with newly diagnosed malignancy.