AbstractBacterial cellulose is a natural biopolymer with an ultrafine nanofibrous reticulated matrix and crosslinking active sites. In this work, composite silica aerogels were prepared using a two‐step acid‐base catalysis and ambient pressure drying, with methyltriethoxysilane as the silica precursor and a trace amount of bacterial cellulose as the silicon skeleton reinforcement. The preparation was carried out in water without the addition of other organic solvents and without solvent replacement. The preparation conditions were optimized, and the prepared composite aerogels were characterized using SEM, BET, FTIR, a contact angle meter, and GA‐DTA. The results showed that the introduction of a trace amount of bacterial cellulose could obviously change the morphology and hydrophilicity of the aerogels, and increase its compressive strength up to 5 MPa without significant changes in its specific surface area and density. The addition of bacterial cellulose helped the aerogels maintain its original shape after being heated at high temperatures.