The widespread use and exposure of coumatetralyl (CMTT) has led to its accumulation in the environment and organisms, causing damage to ecosystems and adverse health effects in humans. Unfortunately, achieving fast detection of CMTT remains challenging. Herein, a rapid and robust surfaceenhanced Raman spectroscopy (SERS) method was developed for rapid on-site detection of CMTT in environmental water and human urine. Clear trends were observed between the signal intensity and the logarithmic concentration of CMTT, ranging from 0.025 to 5.0 μg/mL with high reproducibility. The detection limits in water and human urine were as low as 1.53 and 13.71 ng/mL, respectively. The recoveries of CMTT for environmental water and urine samples were 90.2−98.2 and 82.0−87.5%, respectively, satisfactory for practical applications. The quantitative results of this approach were highly comparable to those obtained by highperformance liquid chromatography. Most importantly, it is cost-effective, operationally simple, and without a complicated sample preparation step. Detecting CMTT in water samples took only 5 min, and the detection of urine samples was completed within 8 min. This simple yet practical SERS approach offers a reliable application prospect for on-site CMTT detection in environmental water and point-of-care monitoring of poisoned patients.