Cyanide released from mostly industrial production is a highly toxic chemical. Its heavy industrial use and transportation increase the danger of human exposure. Since it can often lead to rapid death, selective, sensitive and on-site and rapid monitoring techniques for the detection of cyanide are essential. Therefore, we report an efficient cyanide probe based on thiazolium conjugated HBT-Br derivative. It has striking color change toward cyanide blue to yellow under daylight or colorless to cyan under UV-light. Interaction modes of the probe are based on ESIPT and ICT processes. It is selectively able to react free aqueous cyanide with detection limit of 1.79 μM, lower than physiologically lethal blood levels, >20 μM. Smartphone assisted and test kit applications are able to detect cyanide, qualitatively. Moreover, real samples such as tap or lake water and apricot seeds including cyanide are successfully determined through the present probe. Therefore, the designed probe displays excellent practical potential toward cyanide.