Nanozymes are a new generation of artificial enzymes that enable biological catalysis using nanomaterials. In 2007, Yan and colleagues discovered that ferromagnetic nanoparticles exhibited peroxidase-like activity, laying the foundation for nanozymes. In 2013, Wei and Wang introduced the term "nanozymes" to describe nanomaterials with enzyme-like properties. Nanozymes are attractive due to their high activity, stability, tunability, multifunctionality, and low cost. Over the past 16 years, nanozymes have become an interdisciplinary field, with over 420 laboratories from 42 countries reporting more than 1200 types of nanozymes and publishing over 10,000 papers. Nanozymes can now be rationally designed, showing comparable or better performance than natural enzymes. They have potential applications in functional nanomaterials, biomedicine, new energy, green synthesis, and environmental treatment. Nanozymes were selected as one of the Top Ten Emerging Technologies in Chemistry by IUPAC in 2022. This special issue presents 25 papers, including 9 reviews, 4 perspectives, and 12 research articles, covering rational design, mechanisms, and applications. The issue highlights the evolution of nanozyme definitions, reaction mechanisms, and unique features. It also discusses strategies for improving catalytic performance, including machine learning, biosystem-inspired design, and surface engineering. The issue includes case studies on specific nanozymes for applications such as disease diagnostics, therapeutic effects, and targeted treatment. The authors emphasize the importance of nanozymes in biomedical and environmental applications, with a focus on their potential for future research and development. The authors declare no conflict of interest.Nanozymes are a new generation of artificial enzymes that enable biological catalysis using nanomaterials. In 2007, Yan and colleagues discovered that ferromagnetic nanoparticles exhibited peroxidase-like activity, laying the foundation for nanozymes. In 2013, Wei and Wang introduced the term "nanozymes" to describe nanomaterials with enzyme-like properties. Nanozymes are attractive due to their high activity, stability, tunability, multifunctionality, and low cost. Over the past 16 years, nanozymes have become an interdisciplinary field, with over 420 laboratories from 42 countries reporting more than 1200 types of nanozymes and publishing over 10,000 papers. Nanozymes can now be rationally designed, showing comparable or better performance than natural enzymes. They have potential applications in functional nanomaterials, biomedicine, new energy, green synthesis, and environmental treatment. Nanozymes were selected as one of the Top Ten Emerging Technologies in Chemistry by IUPAC in 2022. This special issue presents 25 papers, including 9 reviews, 4 perspectives, and 12 research articles, covering rational design, mechanisms, and applications. The issue highlights the evolution of nanozyme definitions, reaction mechanisms, and unique features. It also discusses strategies for improving catalytic performance, including machine learning, biosystem-inspired design, and surface engineering. The issue includes case studies on specific nanozymes for applications such as disease diagnostics, therapeutic effects, and targeted treatment. The authors emphasize the importance of nanozymes in biomedical and environmental applications, with a focus on their potential for future research and development. The authors declare no conflict of interest.