This study underlines the idea of valorizing vegetable waste in a “green” approach for water bioremediation. In this research, the possibility of using unpurified peroxidase obtained from cabbage leaf waste in the process of removing phenol from aqueous solutions was examined. This biocatalyst exhibits catalytic activity in a wide range of temperatures, pH values, and pollutant concentrations. The efficiency of phenol removal was monitored spectrophotometrically, by measuring the change in the residual amount of phenol in the reaction mixture. The influence of peroxidase, phenol, hydrogen peroxide, and polyethylene glycol (PEG) concentrations, as well as incubation time, temperature, pH value, and shaking rate on the efficiency of the phenol removal process, was comprehensively evaluated. The results showed that the use of raw, unpurified peroxidase from cabbage leaf waste can successfully replace commercial peroxidase and thereby significantly reduce the procedure cost. In addition, the presence of PEG as a peroxidase stabilizer showed little effect on the phenol removal efficiency, indicating that the extracted crude peroxidase is stable even without a commercial stabilizer, which could further cheapen the phenol removal process.