Broadband high transmittance, humidity resistance and mechanical robustness are three important aspects that dictate the practical applications of antireflective thin films. However, it has proved difficult to harness these properties. In the current work, hybrid thin films with hydrophobic groups in the film framework were prepared from acid catalyzed methyl–silica sols, which simultaneously demonstrate broadband high transmittance, function durability as well as mechanical robustness. The optimized thin film has a maximum transmittance of nearly 100% and an average transmittance of 99.3% in the visible light region on K9 glass, and such impressive antireflective properties are discussed in terms of film porosity and surface morphology. The humidity resistance of thin films was investigated by damp heat test, and the significant humidity resistance is attributed to rich hydrophobic groups in contrast to conventional hydrophilic silica thin films. The mechanical strength of thin films was investigated by the pencil hardness test, washability test as well as adhesion test, and the optimized thin film shows good robustness with 5A adhesion, 3H pencil hardness, and resistance to the washability test.