In recent decades, sol-gel technology has attracted considerable attention in the conservation and restoration of cultural heritage as a nanotechnology-based approach. Features such as the production of organic-inorganic nanocomposites, suitable penetration into porous substrates, formation of thin protective coatings, and resistance to moisture and ultraviolet radiation have expanded its applications in conservation studies. This review examines the capabilities and limitations of sol-gel technology in stone consolidation, protective coatings for historical materials, and environmental monitoring sensors. The reviewed studies indicate that alkoxysilane-based compounds improve the structural cohesion of historical stones and reduce moisture penetration. In addition, sol-gel coatings have shown promising results in protecting metals, glass, tiles, and paper against corrosion, weathering, and microbial growth. Sol-gel-based sensors have also been applied for monitoring humidity, acidity, pollutants, and light in museum environments. Despite these advances, further long-term studies remain necessary.