Abstract: To mitigate poor miscibility, low interfacial adhesion, and inadequate compatibility between hydrophobic SiO₂ aerogels (SA) and inorganic cementitious materials, surface-modified SA slurries with various nonionic surfactants were compounded with inorganic cementitious materials, and their composite performance was systematically investigated. It was found that nonionic surfactants effectively regulated the dispersion behavior and interfacial structure of SA within the cementitious matrix. Composites prepared with nonylphenol ethoxylate-modified SA exhibited superior overall performance relative to other modified samples. At a modified SA slurry addition level of 40 wt%, the resultant composites were characterized by a density of 1322.2 kg/m³, compressive strength of 10.53 MPa, thermal conductivity of 0.3381 W/(m·K), and water absorption of 16.2%. The interfacial regulatory mechanism of nonionic surfactants on the SA-inorganic cementitious system was further elucidated. This work provides a critical theoretical basis for the design and fabrication of high-performance aerogel-based composite thermal insulation materials.