Superoxide anion (O₂^•−) is an important ROS in living systems, and rapid and in situ detection of O₂^•− is critical for the in-depth study of its roles in the closely related diseases. Herein, we present a “double reaction” type-based fluorescent probe (BZT) for the imaging of O₂^•− in living cells. BZT employed a triflate group as a recognition site for O₂^•−. In response to O₂^•−, the probe BZT underwent double chemical reactions, including the nucleophilic reaction between O₂^•− and triflate, and the cyclization reaction through the other nucleophilic reaction between hydroxyl and cyano group. BZT could show high sensitivity and selectivity to O₂^•−. Biological imaging experiments demonstrated that the probe BZT could be successfully applied to detect the exogenous and endogenous O₂^•− in living cells, and the results suggested that rutin could efficiently scavenge the endogenous O₂^•− induced by rotenone. We expected that the developed probe could provide a valuable tool to investigate the pathological roles of O₂^•− in relevant diseases.