We evaluated the magnitude and function of antibody responses to seasonal influenza vaccination in individuals with HIV receiving ART compared with individuals without HIV. In a prospective cohort of 78 adults, influenza strain-specific IgG levels were measured up to one-year post-vaccination. Linear mixed-effects models assessed longitudinal trends. IgG levels peaked at two weeks and declined gradually in both groups. HIV status did not significantly influence antibody magnitude or neutralizing activity, and H1N1 antibody levels correlated with neutralization titers. These findings demonstrate robust, durable, and functional humoral response in well-controlled HIV, supporting the effectiveness of annual influenza vaccination in this population.