Group A Streptococcus (Strep A) is a globally important pathogen for which no licenced vaccine currently exists. Defining the immunological basis of protection is critical to identifying a correlate of protection, a key element for future vaccine development. Understanding Strep A immunity is challenging due to the complex interplay between diverse virulence factors and immune system components. Here, we use a high-dimensional Strep A-specific systems serology array to identify correlates of a functional immune response in pharyngitis. The array quantifies 121 antibody features, including isotypes, Fc receptor and complement binding, and was engineered to detect both conserved and type specific (M6/T6) responses. This approach was combined with opsonophagocytic killing assays (OPKA) and applied to children with pharyngitis caused by emm6 and non-emm6 strains, as well as healthy controls. Systems serology tools were used to identify serological features linked to pharyngitis and type-specific killing. Total IgG responses to conserved antigens were higher in both pharyngitis groups, while IgG3 responses were most prominent for type specific antigens (M6/T6) and in children with emm6 pharyngitis. Multivariate analysis linked M-type-specific antibody responses and engagement of the activating Fc receptor (FcγRIIa) with functional killing. This feature was able to predict killing with 100% accuracy in a distinct set of sera, confirming identification of a correlate of a functional antibody responses for emm6 strains in children. Broader application of this systems serology approach could aid in deconvoluting the Strep A immune response, with potential to identify correlates of protection in future vaccine trials.