A pioneering aggregation-induced emission (AIE) fluorescent compound, PCBO, has been engineered initially, combining oxalyl di-hydrazide and a phenylcarbazole derivative. When tested in a THF/H2O solution with a fraction of water (fw) at 70 %, the compound reveals superior selectivity, interference-resilience, and expansive pH range. Additionally, it manifests as a recyclable 'turn-off' fluorescent sensor for Cu2+ in an aqueous medium, with a detection limit (LOD) standing impressively low at 1.6 × 10−7 M. The coordination ratio that emerges between PCBO and Cu2+ is maintained at 2:1, alongside a binding constant of approximately 3.18 × 1011 M−2. The testing paper generated demonstrates commendable performance in the measurement of Cu2+ in water samples. The working principle of the fluorescence mechanism is theorized and established through sophisticated simulation calculations.