A novel naked-eye colorimetric and ratiometric fluorescent probe (B-ClO) was transformed from anthracene-hydrazone to anthracene-triazole based on a HClO-mediated cyclization reaction with an F_{434 nm}/F_{570 nm} ratio in quantitative response to HClO. The B-ClO probe exhibited high sensitivity (limit of detection of 14 nM) and a fast response time to ClO⁻ over other competing species as well as across a wide pH range. Study of the sensing mechanism supported a HClO-mediated cyclization reaction in which 1,2,4-triazole forms via HClO and a hydrazone derivative, with excellent photophysical properties. Such a probe was used as B-ClO test strips and B-ClO silica materials to monitor HClO in the environment, exhibiting excellent solid properties.