This study reports a scalable Langmuir-Blodgett technology for fabricating monolayer hexagonal close-packed silica colloidal crystal/polyethoxylated trimethylol-propane triacrylate composites on polyethylene terephthalate (PET) substrates. The silica colloid monolayers can be further etched to pattern nanohole structure arrays directly on PET substrates. The resulting nanosphere and nanohole structure arrays exhibit omnidirectional broadband antireflective properties. After surface modification, the surface hydrophobicity and self-cleaning property can be improved.