<p>Clay-based geopolymers have emerged as promising low-carbon alternatives to conventional Portland cement, driven by the need for sustainable construction materials. This review systematically synthesizes literature on clay-based geopolymers, focusing on mineralogy, activation methods, and microstructural influences on construction performance. The aim is to provide a comprehensive understanding of how clay mineralogy governs geopolymerization behavior, microstructural evolution, and engineering properties. The scope of this study includes a wide range of clay precursors, such as kaolinitic, illitic, smectitic, fibrous, and lateritic systems, along with their respective activation and treatment strategies. Emphasis is placed on establishing relationships between mineralogical characteristics, reaction mechanisms, and performance indicators, including mechanical strength, durability, and transport properties. In addition, the review highlights recent advances in characterization techniques and the growing role of statistical and reliability-based approaches in evaluating material performance. The significance of this work lies in integrating mineralogical insights with performance-based design to support the development of reliable and scalable geopolymer systems. Furthermore, the study discusses the potential of clay-based geopolymers in advancing sustainable and climate-resilient construction practices. Clay-based geopolymer binders align with UN Sustainable Development Goals 9, 11, 12, and 13, fostering sustainable infrastructure development and climate-resilient construction practices.</p>