Pinewood biochar was prepared and modified with KOH and used for the immobilization of CuO for efficient adsorption and degradation of model pharmaceutical compounds including ciprofloxacin and carbamazepine from polluted waters. Techniques used were X-ray diffraction, Scanning electron microscopy, Fourier transmission infrared spectroscopy, Brunauer–Emmett–Teller surface area and porosity analysis, which indicated that specific surface area of K-BC was ten-times higher than that of the pristine BC. More functional groups, such as C-N, COO–, and C = C were present onto the surface of the modified BC, which facilitated the adsorption of pollutants to promote degradation reactions. K-BC-CuO showed complete degradation of the pharmaceuticals in the presence of persulfate (PS). The response surface methodology revealed that the effects of various operating parameters on the degradation of CBZ, which followed the sequence: temperature > PS concentration > initial CBZ concentration > K-BC-CuO dosage > pH. The degradation mechanisms were investigated to prove that singlet oxygen is the dominant species for CIP and CBZ degradation. This research provides new insights into the fabrication and application of sustainable and green materials for the removal of emerging wastewater contaminants.