Cement production significantly contributes to global CO₂ emissions. Limestone Calcined Clay Cement (LC³)—a mixture of limestone, calcined clay, cement clinker, and gypsum—offers a promising alternative by significantly reducing clinker contents without compromising mechanical performance. This study assesses the environmental and social hotspots of various LC³ mortars produced in Germany, a context not yet explored in previous research. While prior studies have mostly focused on LC³ in concrete applications and in low- to middle-income countries, this is the first to evaluate LC³-based mortar in a high-income, highly industrialized context using both Life Cycle Assessment (LCA) and Social Risk Assessment (SRA) to determine the main environmental and social drivers of this material. The LCA revealed that LC³ mixtures achieve substantial reductions in key impact categories compared to conventional Ordinary Portland Cement (OPC) mixes, including Climate Change (up to 42.6% reduction) and Particulate Matter (up to 15.8% reduction). The SRA highlights significant social risks related to corruption, fair competition, and workers’ rights, including fair wages, discrimination, and safe working conditions. This study underscores LC³ as a promising sustainable solution in cement applications while emphasizing the importance of region-specific assessments to address unique environmental and social considerations.