Recently, nanomaterial-based enzyme mimetics (nanozymes) have attracted enormous interest. They exhibit unique advantages such as excellent robustness, stability, and low-cost production with easy scale-up, which are critically needed as an alternative to natural enzymes. These nanozymes exhibit natural enzyme-like activity and have been applied to various kinds of detection and treatment methods for biomolecules such as DNA, proteins, cells, and small molecules including glucose. To highlight progress in the field of nanozymes, this review discusses recent nanozyme-based research results and their applications for the development of novel biosensor, immunoassay, cancer diagnostics, therapeutics, and environmental engineering technologies. Current challenges and future prospects of nanozymes for widespread use in biotechnology are also discussed.