The catalyst of CuOx/granular activated carbon (GAC) was prepared and used as a heterogeneous Fenton-like catalyst for degradation of phenol in the microwave (MW)-induced H2O2 catalytic oxidation process. The prepared catalysts were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS), X-ray diffraction (XRD), and N2 adsorption–desorption techniques. Results showed that CuO and Cu2O were loaded on the surface of GAC. Effects of catalyst dosage, H2O2 dosage, pH, MW power, and MW irradiation time on the degradation efficiency were studied. The phenol degradation efficiency reached 99.96%, corresponding to 88.6% chemical oxygen demand (COD) removal under optimal conditions with MW power of 400 W, CuOx/GAC dosage of 3 g/L, H2O2 dosage of 2 mL/L, reaction time 4 min, and pH 4. The combined method of MW/catalyst/H2O2 has been proven to be much more effective toward phenol degradation than using MW alone, catalyst alone, MW/catalyst, MW/H2O2, and catalyst/H2O2 methods. In the presence of CuOx/GAC catalyst, the mechanism of phenol degradation under MW irradiation combined with H2O2 was suggested. A synergistic effect of catalyst, MW, and H2O2 contributes to the high degradation efficiency of phenol. The obtained kinetic equation for MW catalytic oxidation degradation of phenol was in line with first-order kinetic model.