Nanocomposite hydrogels are advanced biomaterials that combine nanoparticles with polymeric networks to enhance physical, chemical, electrical, and biological properties. These materials are used in biomedical applications such as tissue engineering, drug delivery, biosensors, and bioactuators. The integration of various types of nanoparticles—carbon-based, polymeric, inorganic, and metal/metal-oxide—into hydrogel networks allows for tailored functionality and improved performance. Carbon-based nanoparticles like carbon nanotubes (CNTs) and graphene enhance mechanical and electrical conductivity, while inorganic nanoparticles such as hydroxyapatite and silica improve bioactivity and mechanical strength. Metal and metal-oxide nanoparticles, including gold and silver, offer antimicrobial and conductive properties. The incorporation of these nanoparticles into hydrogels enables the development of stimuli-responsive materials that can respond to environmental changes, such as temperature or pH, for controlled drug release or tissue engineering. Challenges include ensuring biocompatibility, controlling nanoparticle dispersion, and optimizing mechanical and biological properties. Future research aims to design more advanced nanocomposite hydrogels with enhanced functionality, improved biocompatibility, and better integration with biological systems. These materials hold significant potential for biomedical and biotechnological applications due to their unique properties and versatility in design.Nanocomposite hydrogels are advanced biomaterials that combine nanoparticles with polymeric networks to enhance physical, chemical, electrical, and biological properties. These materials are used in biomedical applications such as tissue engineering, drug delivery, biosensors, and bioactuators. The integration of various types of nanoparticles—carbon-based, polymeric, inorganic, and metal/metal-oxide—into hydrogel networks allows for tailored functionality and improved performance. Carbon-based nanoparticles like carbon nanotubes (CNTs) and graphene enhance mechanical and electrical conductivity, while inorganic nanoparticles such as hydroxyapatite and silica improve bioactivity and mechanical strength. Metal and metal-oxide nanoparticles, including gold and silver, offer antimicrobial and conductive properties. The incorporation of these nanoparticles into hydrogels enables the development of stimuli-responsive materials that can respond to environmental changes, such as temperature or pH, for controlled drug release or tissue engineering. Challenges include ensuring biocompatibility, controlling nanoparticle dispersion, and optimizing mechanical and biological properties. Future research aims to design more advanced nanocomposite hydrogels with enhanced functionality, improved biocompatibility, and better integration with biological systems. These materials hold significant potential for biomedical and biotechnological applications due to their unique properties and versatility in design.