Background <p>Cytomegalovirus (CMV) is a ubiquitous herpesvirus with nearly universal seroprevalence in sub-Saharan Africa. In people living with HIV, CMV contributes to immune activation, systemic inflammation, and accelerated immune dysfunction despite virologic suppression on antiretroviral therapy (ART). Data on CMV–HIV co-infection remain scarce in North-East Nigeria, where fragile health systems and late presentation to care are common.</p> Methods <p>We conducted a cross-sectional study among 181 adults with confirmed HIV receiving ART at the Federal Teaching Hospital, Gombe. Socio-demographic and clinical data were collected using structured questionnaires and patient records. Serum samples were tested for CMV immunoglobulin G (IgG) and immunoglobulin M (IgM) antibodies using ELISA. CD4 + T-cell counts and HIV viral load were measured using flow cytometry and real-time PCR.</p> Results <p>All participants (181/181; 100%) were CMV IgG positive, confirming universal prior exposure. CMV IgM seropositivity—indicating recent or ongoing infection—was detected in 58 of 181 participants (32.1%). IgM-positive cases were distributed across all age groups and were more frequent among women. Patterns of IgM seropositivity across CD4 + T-cell and viral load categories reflected the underlying distribution of clinical characteristics in the cohort.</p> Conclusion <p>This study provides the first evidence of universal CMV exposure and a substantial prevalence of recent or reactivated infection among adults with HIV on ART in North-East Nigeria. The presence of CMV IgM positivity in a clinically stable, largely virologically suppressed population highlights CMV’s persistent immunologic relevance. Further research using molecular assays is warranted to clarify the role of CMV reactivation in immune dysfunction and long-term ART outcomes.</p> Clinical trial <p>Not applicable.</p>