Herein, an aggregation-induced emission (AIE)-based sensor, 4-(1,2,2-triphenylvinyl)benzoxime (TPE-phos), has been rationally designed for phosgene detection. The sensor has a tetraphenylethylene unit combined with an oxime moiety. TPE-phos undergoes nitrile formation after the oxime group reacts with phosgene, which will give a significant "light-up" fluorescence due to the AIE effect within seconds.