Photonic crystal structures attract much interest, and considerable efforts have been devoted toward hydrogel-based photonic crystal responsive materials. However, the mechanical strength of such composite films is still not desirable. Here, we present a light diffracting hydrogel film with enhanced mechanical property by embedding a self-assembled polystyrene array in a binary hydrogel via a facile photopolymerization technique, which enables the convenient fabrication and shaping of robust photonic sensing films.