γ-Dicalcium silicate (γ-C₂S)-based carbonatable binder is a novel low-carbon cementitious material featuring rapid hardening, high strength, and permanent CO₂ sequestration. However, during actual production, the use of industrial raw materials or solid wastes introduces iron and aluminum impurities into the original calcium‑silicate system, forming ferrite solid solutions (Ca₂Al_xFe_2-xO₅, 0≤x<1.4) upon high‑temperature calcination. Existing studies generally consider the intrinsic carbonation reactivity of ferrite phases to be low, yet their role in the composite system of carbonatable binders remains unclear. In this study, a typical ferrite phase composition, tetracalcium aluminoferrite (C₄AF), was selected to systematically reveal its influence on the carbonation performance of γ-C₂S ‑based carbonatable binders. High‑purity C₄AF single mineral and γ-C₂S‑based carbonatable binder were prepared, and the carbonation performance as well as the composition and structure of the products of samples with different C₄AF contents were characterized by ICP, QXRD, SEM, and other techniques. The results show that C₄AF plays a significant promoting role in the γ-C₂S‑based carbonatable binder system. At a C₄AF content of 30 wt.%, the compressive strength of the carbonated specimens increased by 53.25%, reaching 120.9 MPa. On one hand, C₄AF inhibits the vigorous exothermic reaction at the early carbonation stage and slows down water evaporation, thereby creating favorable conditions for sustained later‑stage reactions. On the other hand, it regulates the calcium carbonate polymorph, significantly increasing the content of nano‑sized vaterite and effectively reducing the porosity of the products. This study provides an important theoretical basis for optimizing the composition design of carbonatable binder and the efficient utilization of iron‑ and aluminum‑containing solid waste.