Extensive application of nuclear energy has caused widespread environmental uranium contamination. New detection approaches without complicated sample pretreatment and precision instruments are in demand for on-site and in-time determination of uranyl ions in environmental monitoring, especially in an emergency situation. In this work, a simple and effective fluorescent sensor (Z)-N'-hydroxy-4-(1,2,2-triphenylvinyl)benzimidamide (TPE-A) with aggregation-induced emission (AIE) character was established and studied. It could realize to detect UO₂²⁺ via quenching the fluorescence of its aggregation-induced emission, with good selectivity and sensitivity. Such strategy shows a wide linear range from 5.0 × 10⁻⁸ mol/L to 4.5 × 10⁻⁷ mol/L (R² = 0.9988) with exceptional sensitivity reaching 4.7 × 10⁻⁹ mol/L, which is far below the limit for uranium in drinking water (30 μg/L, ca. 1.1 × 10⁻⁷ mol/L) stipulated by the WHO. A response time less than four minutes make it rapid for uranyl ion measurement. It was applied for detection of uranyl ion in spiked river water samples with recoveries in the range of 98.7%-104.0%, comparable to those obtained by ICP-MS. With the advantages of portable apparatus, rapid detection process and high sensitivity, TPE-A can serve as a promising fluorescent sensor for the detection of UO₂²⁺ in environmental water samples.