Cement production is responsible for approximately 8% of global CO₂ emissions, necessitating the development of sustainable alternatives. One widely studied approach involves the use of supplementary cementitious materials (SCMs), such as limestone and calcined clays, to partially replace ordinary Portland cement (OPC). Among these, Limestone Calcined Clay Cement (LC3) has demonstrated potential in reducing carbon footprints while maintaining mechanical performance. Despite the extensive study of LC3 binding systems, recent advancements in carbon reduction and utilization technologies have enabled the scalable production of vaterite, a metastable and more reactive polymorph of calcium carbonate. This development presents a promising but underexplored opportunity for sustainable binder production. This study examines Vaterite Calcined Clay Cement (VC3) as a sustainable binder, focusing on how the metakaolin-to-vaterite (MK/V) ratio influences workability, microstructure, and mechanical properties. By addressing this gap, this research contributes to optimizing VC3 formulations and advancing low-carbon cement technology.