Carbon fiber reinforced concrete (CF-C) has emerged as a sustainable alternative in construction, offering enhanced durability and lightweight design opportunities due to the excellent corrosion-resistance of the carbon fiber (CF) reinforcements. However, the thinner cross-sections of typical CF-C structures pose increased vulnerability to structural and environmental damages, particularly under freeze-thaw (FT) conditions and cracking issues. A novel mineral-impregnated carbon fiber reinforcement (MCF) integrates advantageous properties of mineral materials with CF, providing economic benefits, enhanced physicochemical compatibility with cementitious matrices and superior mechanical performance across a broad temperature range. While CFs remain structurally stable over a wide range of temperatures, FT-induced cracking within the impregnation matrix will significantly compromise reinforcement efficiency and long-term durability. This concern for frost durability reamains underexplored before entering the key market. In this study, a novel MCF reinforcement type based on limestone calcined clay cement (LC3), recognized for its superior CO₂ reduction potential for construction, is developed and evaluated for its applicability in severe environmental conditions. The impact of FT cycling on the mechanical integrity and microstructural evolution of LC3-based MCF reinforcements is assessed. Specimens are subjected to FT cycles following DIN CEN/TS 12390–9 standards, while a control group is stored at 20 ℃ and 65% relative humidity (RH) for 28 days. Three-point bending tests were conducted to evaluate mechanical performance degradation, supplemented by morphological analysis to characterize crack propagation. The findings contribute to a deep understanding of frost-induced damage mechanisms in MCFs, providing insights into enhancing the durability and sustainability of next-generation structural materials.