Cellulose hydrogels are a class of sustainable natural polymeric materials with good biocompatibility, high water retention and degradability. By loading inorganic nanostructures such as metals, metal oxides, carbon-based materials, ceramics and clays as well as inorganic salt ions onto the cellulose gel matrix, precise modulation of functional properties can be achieved. Specific strategies include in-situ synthesis and deposition, physical mixing and chemical cross-linking to homogeneously disperse the nanostructures and firmly fix them in a three-dimensional network. These composite systems present a rich variety of functions, such as electrical conductivity, magnetism, photocatalysis and antimicrobial properties. The research hotspots focus on the preparation and property modulation of composites such as cellulose/inorganic nanomaterials, and show promising applications in the fields of flexible electronic sensing, biomedical dressings, environmental pollution control and sustainable energy. This chapter summarizes the functional modulation strategies, research progress and challenges of various types of inorganic nanomaterials modifying cellulose-based hydrogels, and looks forward to their future development in areas such as wearable devices, smart biomaterials and environmental governance.