Cancer is one of the most serious threats to human health. Over the past few years, researchers have incrementally uncovered the pivotal role of tumor acidity in tumor formation, development and treatment through in‐depth scientific research. In addition, bioorthogonal reactions have been widely used in tumor diagnosis and therapy, owing to their advantageous characteristics, including small ligand size, biocompatibility, fast reaction kinetics, and high chemospecificity. Consequently, bioorthogonal reactions triggered by tumor acidity have become an emerging strategy in biomedical applications. On this basis, we introduce the concept and major strategies of tumor acidity‐triggered bioorthogonal reactions, and review their progress in biomedical applications, with a particular focus on their importance in disease diagnosis and treatment. Finally, clinical challenges and future trends are also outlooked.