<p>Expansive soils pose geotechnical challenges due to significant volume changes with moisture variations. The Kingdom of Saudi Arabia (KSA), with its diverse geology and climate, contains extensive deposits of expansive soils that require systematic assessment. This study compiles and analyzes data on the distribution, geological origin, geotechnical behavior, and mineralogical composition of expansive soils in key regions, including Al-Ghatt, Tayma, Tabuk, Al-Madinah, Hofuf, Al-Qatif, and Sharorah. The findings show that expansive soils in KSA cover about 37% of the country’s total area and occur across nine of its thirteen provinces. Their formation results from geological history, sedimentary processes, and severe weathering under arid conditions. Geotechnical data reveal significant regional variability in properties such as specific gravity (2.24–2.96), liquid limit (30–183.5%), Clay content (10– 93%) Shrinkage limits (9 to 47.2%) and swelling pressure (14–1930 kN/m²), reflecting differences in mineralogy and soil structure. The mineralogical composition of expansive soils in KSA varies regionally, influenced by geology and climate. Future research should focus on expanding mineralogical and geotechnical investigations in underexplored regions. Standardized testing methods should be adopted across studies to improve data consistency and regional comparison. Moreover, integrating remote sensing and GIS will enhance expansive soil mapping and risk assessment across KSA.</p>