The creation and construction of smart chemosensors that respond to a large variety of external stimuli, such as temperature, pH, redox, molecular recognition, photoirradiation, and forces (grinding and pressure), are of particular significance in current chemistry. Such chemosensors will enable not only the quantification of the mechanical properties of novel soft materials but also measure biological events in living tissues. Nevertheless, conventional signaling by outputting such external stimuli currently relies on regular dyes that emit fluorescence, showing an aggregation-caused quenching (ACQ) effect that hampers better chemosensing. In 2001, Tang et al. discovered a serendipitous aggregation-induced emission (AIE) chromophore that overcomes the inherent drawbacks of ACQ. Many researchers have since joined the relatively new field of “AIE chemistry,” from which the growing field of AIE-active chemosensors has emerged. In this chapter, we introduce smart AIE-based chemosensors that respond to external stimuli.