Photopolymerization is the most widely used method to fabricate hydrogels, which hold great potentials in various fields including biomedical applications, electronic skin and flexible wearable devices. Herein, we employed gold nanoclusters (AuNCs) both as efficient photo-initiator and crosslinker to prepare polyacrylamide (PAM) hydrogel with good mechanical properties. Firstly, an imidazole-based monomer was designed and synthesized, named as ImPAA, which served as reducing agent and ligands to prepare imidazole-stabilized AuNCs (AuNC@ImPAA) in water. Under white light irradiation, AuNC@ImPAA can efficiently initiate the radical polymerization of acrylamide monomer in water via a photocatalytic mechanism. The abundant vinyl bonds on surface of AuNC@ImPAA endowed it as a multiple covalent crosslinker and led to the final hydrogel possessing promising mechanical properties. The maximum tensile strength and the fracture strain was 287 kPa and 591%, respectively. Furthermore, triggered by UV light, the embedded AuNC@ImPAA in hydrogel can aggregate and convert into gold nanoparticles (AuNPs), resulting in AuNP/PAM hydrogel. This hybrid AuNP/PAM hydrogel exhibited a good photothermal conversion performance with an efficiency of 14.14% under 660nm laser irradiation, and its potential as a photothermal actuator was demonstrated. Thus, we provide a facile light-mediated strategy to fabricate functional hydrogel.