The first ratiometric fluorescent probe for hypochlorite has been developed through regulation of the electron‐withdrawing ability of the electron acceptor in an intramolecular charge‐transfer (ICT) system by a deoximation reaction (see figure; EWG=electron‐withdrawing group).

In this work, we have successfully provided a novel strategy for the rational design and synthesis of a ratiometric fluorescent probe for hypochlorite. The strategy is based on the deoximation reaction, which has not yet been used in the fluorescent hypochlorite probe design. Interestingly, the probe showed a ratiometric fluorescent response to hypochlorite with the emission intensities ratio (I₅₀₉/I₄₃₉) increasing from 0.28 to 2.74. Furthermore, the probe displayed high selectivity for hypochlorite over other species due to the distinct deoximation conditions. The probe developed herein represents the first ratiometric fluorescent probe for hypochlorite.