4-hexylresorcinol (4-HR), a natural compound renowned for its innate antibacterial and antioxidant properties, finds pervasive utilization in preventing browning and extending the shelf life of products such as shrimp and crab. The manuscript presents a novel method for expeditious screening and precise quantification of 4-HR in crustacean aquatic products, based on the reaction between 4-HR and dopamine to yield a strongly fluorescent product. The innovative method has remarkable sensitivity, strong anti-interference capabilities, simplicity, and rapidity, thereby facilitating not only on-site screening in just 7.5 minutes but also meticulous in-laboratory detection with enhanced precision. The fluorescence intensity has a linear relationship with 4-HR content in the range of 0-100 μg/g, with a detection limit of 0.006 μg/g. The proposed method has the potential to become a standard for determining 4-HR in crustacean aquatic products, addressing limitations of existing techniques like high-performance liquid chromatography, which are complex and costly. This methodology holds great promise in ensuring the safety of crustacean aquatic products and has the potential to become the standard method for 4-HR determination.