People living with HIV have accounted for 38–50% of those affected in the 2022 multicountry mpox outbreak. Most reported cases were in people who had high CD4 cell counts and similar outcomes to those without HIV. Emerging data suggest worse clinical outcomes and higher mortality in people with more advanced HIV. We describe the clinical characteristics and outcomes of mpox in a cohort of people with HIV and low CD4 cell counts (CD4 <350 cells per mm3).