Mechanochemistry has emerged as a powerful strategy for controlling chemical reactivity and tuning material properties through applied force. Within this growing field, mechanochromic mechanophores have attracted particular attention as versatile molecular probes that transduce mechanical inputs into optical signals via force-induced structural transformations. By enabling direct visualization of stress and damage in real time, these systems provide unique opportunities for applications in stress sensing, damage detection, and the design of adaptive materials. This Review offers a systematic framework of classifying mechanochromic mechanophores, with a focus on their molecular design principles and activation mechanisms. We highlight how methods of force application and characterization critically shape the study of mechanochromism and examine how mechanophore scaffolds, polymer architectures, and environmental factors collectively dictate optical responses. Applications are critically assessed to underscore the role of mechanochromic systems as a bridge between fundamental mechanochemistry and functional materials engineering. Finally, we outline current challenges and emerging opportunities, with particular emphasis on the growing potential of mechanochromic systems in biological and biomedical contexts.