Highly toxic phosgene, mustard gas, and nerve agents as chemical warfare agents (CWAs) seriously threaten public security and human life. Therefore, it is a great demand to develop effective approaches for monitoring CWAs in a rapid, sensitive, and convenient manner. Molecular engineered optical probes have emerged as a promising technology for monitoring various CWAs due to their high sensitivity, facile operation and visual signal readout. This review comprehensively summarizes the recent innovations regarding reaction sites, working mechanisms and sensing properties of various molecular engineered optical probes for phosgene, sulfur mustard gas, nerve agents and their mimics. Specific attention is given to the fundamental principles and strategies for designing sensitive and selective optical probes for diverse CWAs. Furthermore, we point out the current trends and challenges, and propose the future directions of molecular engineered probes for sensing CWAs. We envision that this comprehensive and timely review will provide important guidance for practitioners and beginners to develop future molecular probes in relevant research fields.