This review provides an overview of click chemistry reactions and their suitability for biomedical applications, emphasizing the importance of reaction rates. Click chemistry, initially developed by Sharpless and colleagues, involves a set of reactions that produce simple, fast, and high-yield compounds with modular, wide-applicability, and benign byproducts. The review highlights the benefits and limitations of well-established click chemistry reactions, including cycloadditions, nucleophilic ring-opening reactions, non-aldol carbonyl reactions, and additions to carbon–carbon multiple bonds. It discusses the selection criteria for choosing the most appropriate reaction, such as selectivity, reactivity, biocompatibility, and stability, with a particular focus on reaction rates. The review details the characteristics and reaction rates of various click chemistry reactions, such as CuAAC, SPAAC, IEDDA, and others. It explains how reaction rates can be influenced by factors like temperature, solvent, pH, and the presence of catalysts. The importance of reaction rates in optimizing conditions for efficient and stable reactions is emphasized, along with the need to balance rapid kinetics with the specific requirements of different biomedical applications. Recent studies in biomedical research, including drug delivery, imaging, and cancer therapy, are discussed to illustrate the practical application of click chemistry. For example, CuAAC has been used to modify anticancer agents and radiolabel high-molecular-weight molecules, while IEDDA has shown promise in pre-targeting approaches and lipid research. The review also highlights the challenges and limitations of using certain click reactions, such as the toxicity of copper catalysts and the stability of products under physiological conditions. Overall, the review aims to guide researchers in selecting the most suitable click chemistry reaction for their specific biomedical applications by providing a comprehensive understanding of the reaction rates and their implications.This review provides an overview of click chemistry reactions and their suitability for biomedical applications, emphasizing the importance of reaction rates. Click chemistry, initially developed by Sharpless and colleagues, involves a set of reactions that produce simple, fast, and high-yield compounds with modular, wide-applicability, and benign byproducts. The review highlights the benefits and limitations of well-established click chemistry reactions, including cycloadditions, nucleophilic ring-opening reactions, non-aldol carbonyl reactions, and additions to carbon–carbon multiple bonds. It discusses the selection criteria for choosing the most appropriate reaction, such as selectivity, reactivity, biocompatibility, and stability, with a particular focus on reaction rates. The review details the characteristics and reaction rates of various click chemistry reactions, such as CuAAC, SPAAC, IEDDA, and others. It explains how reaction rates can be influenced by factors like temperature, solvent, pH, and the presence of catalysts. The importance of reaction rates in optimizing conditions for efficient and stable reactions is emphasized, along with the need to balance rapid kinetics with the specific requirements of different biomedical applications. Recent studies in biomedical research, including drug delivery, imaging, and cancer therapy, are discussed to illustrate the practical application of click chemistry. For example, CuAAC has been used to modify anticancer agents and radiolabel high-molecular-weight molecules, while IEDDA has shown promise in pre-targeting approaches and lipid research. The review also highlights the challenges and limitations of using certain click reactions, such as the toxicity of copper catalysts and the stability of products under physiological conditions. Overall, the review aims to guide researchers in selecting the most suitable click chemistry reaction for their specific biomedical applications by providing a comprehensive understanding of the reaction rates and their implications.