The article reviews the current developments in the synthesis, properties, and biomedical applications of stimuli-responsive nanogels. These nanogels, which can respond to various environmental stimuli such as pH, temperature, light, and magnetic fields, have gained significant interest in biomedical fields due to their unique environment-sensitive properties. The authors discuss the advantages of nanogels, including good hydrophilicity, high drug loading efficiency, flexibility, and excellent biocompatibility and biodegradability. They also explore the classification of nanogels into physically and chemically cross-linked types, highlighting the importance of cross-linking in controlling nanogel morphology, strength, and swellability. The synthesis aspects of stimuli-responsive nanogels are detailed, including polymerization methods, physical and chemical cross-linking, and template-assisted nanofabrication. The inherent properties of nanogels, such as biocompatibility, degradation, swelling behavior, drug loading capacity, and colloidal stability, are discussed. Additionally, the article covers the biomedical applications of stimuli-responsive nanogels, focusing on single-stimulus systems like pH- and temperature-responsive nanogels, as well as multi-stimuli systems. Examples of drug delivery applications, including cancer treatment and tissue engineering, are provided to illustrate the potential of these nanogels in various therapeutic contexts.The article reviews the current developments in the synthesis, properties, and biomedical applications of stimuli-responsive nanogels. These nanogels, which can respond to various environmental stimuli such as pH, temperature, light, and magnetic fields, have gained significant interest in biomedical fields due to their unique environment-sensitive properties. The authors discuss the advantages of nanogels, including good hydrophilicity, high drug loading efficiency, flexibility, and excellent biocompatibility and biodegradability. They also explore the classification of nanogels into physically and chemically cross-linked types, highlighting the importance of cross-linking in controlling nanogel morphology, strength, and swellability. The synthesis aspects of stimuli-responsive nanogels are detailed, including polymerization methods, physical and chemical cross-linking, and template-assisted nanofabrication. The inherent properties of nanogels, such as biocompatibility, degradation, swelling behavior, drug loading capacity, and colloidal stability, are discussed. Additionally, the article covers the biomedical applications of stimuli-responsive nanogels, focusing on single-stimulus systems like pH- and temperature-responsive nanogels, as well as multi-stimuli systems. Examples of drug delivery applications, including cancer treatment and tissue engineering, are provided to illustrate the potential of these nanogels in various therapeutic contexts.