A simple Zn²⁺-selective chemosensor system based on acylhydrazone was designed and synthesized, which could detect Zn²⁺ ions in aqueous solution with high selectivity and sensitivity over a wide pH range by the mechanism of photo-induced electron transfer (PET). The obvious color changes and pronounced OFF-ON-type fluorescent signaling behavior can be seen by the naked eye. The detection limit of L2 for Zn²⁺ ion was as low as 0.13 μM. In addition, L2–Zn²⁺ complex can be used as an ON-OFF chemosensor candidate for Cu²⁺, as the Zn²⁺-induced emission can be quenched upon addition of Cu²⁺. Moreover, test strips for Zn²⁺ based on L2 were also fabricated, which could be used as a convenient and efficient test kit for instantly detecting Zn²⁺ in aqueous solution.