Hydrogel nanocomposites have been recognized as 'smart materials' owing to their three-dimensional polymeric structures that can easily stabilize the constituent nanomaterials (metals, non-metals, metal oxides, and polymers). In addition, the incorporation of nanomaterials into a hydrogel structure can enhance the properties, such as photonic, electronic, magnetic, chemical, and mechanical properties. These hybrid materials improve the properties of both components d the hydrogel and nanoparticles (NPs) d with stimuli response. In this review, the synthetic approaches for the preparation of nanomaterial-(metal NPs, metal oxide, graphene oxide, carbon dots, and graphene) integrated hydrogels are summarized. We described the applications of nanomaterial-incorporated hydrogels in biomedical sciences (tissue engineering, drug delivery, and wound healing) and in sensing of various target analytes (metal ions, organic, and biomolecules). Finally, we discuss the future prospects of hybrid hydrogels in multidisciplinary research. (c) 2021 Elsevier Ltd. All rights reserved.