Mother-to-child transmission remains the predominant cause of paediatric HIV infection. Despite effective antiretroviral therapy (ART), it remains unclear how paediatric HIV reshapes the development and functional specialization of antiviral T cell immunity beyond HIV-specific responses. Here, we compared antigen-specific memory CD8⁺ and CD4⁺ T cell responses to four common viruses in children (n = 24) and adults living with HIV (n = 40), alongside HIV-negative children (n = 19) and adults (n = 39), matched for cytomegalovirus (CMV) serostatus. Using high-parameter flow cytometry, we show that children living with HIV (CLWH) exhibit a more adult-like memory CD8⁺ T cell compartment, characterized by increased expression of late differentiation markers. CMV- and Epstein–Barr virus (EBV)-specific CD8⁺ T cells displayed enhanced polyfunctionality and cytotoxic potential in CLWH compared with HIV-negative children, whereas responses to acute respiratory viruses were largely preserved. Single-cell RNA sequencing revealed clonal expansion of CMV-specific CD8⁺ T cells and a pro-inflammatory transcriptional bias in antigen-specific CD4⁺ T cells in CLWH. Together, these findings demonstrate that paediatric HIV infection, despite ART, accelerates the maturation and functional specialization of selected antiviral T cell populations, with potential implications for long-term immune health.