In the present study, a magnetic nanocomposite based on biochar (BC) derived from sugarcane bagasse, nanoscale zerovalent iron (nZVI), and chitosan (CS) was fabricated to investigate its efficacy for the removal of two widely used pharmaceutically active compounds (PhACs), namely aspirin (ASA) and carbamazepine (CBZ). The synthesized nanocomposite (BC-CS@nZVI) was characterized using XRD, FTIR, and FESEM-EDX. The Response Surface Methodology–Central Composite Design (RSM-CCD) model was used for the optimization of removal efficacies for both drugs using five variables, i.e., adsorbent dose (0.05–0.1 g), pH (2–10), drug concentration (20–40 ppm), time (40–80 min), and temperature (40–60 °C). Under optimized conditions of adsorbent dose: 0.075 g, pH: 2, drug concentration: 30 ppm, time: 60 min, and temperature: 50 °C, the maximum removal efficiency of ASA drug was observed to be 97.8%, while in the case of CBZ drug under similar conditions with pH 6, the maximum removal was found up to 89.32%. The isotherm models revealed that both ASA and CBZ adsorption data fit well with the Langmuir isotherm showing monolayer adsorption. The kinetics of adsorption was well explained by the pseudo-first- and pseudo-second-order models in the case of ASA and CBZ, respectively. Thermodynamic parameters confirmed the feasibility of the reaction and its spontaneous and exothermic nature. The reusability and efficiency in water samples of the Ha’il region were investigated to demonstrate its potential for practical application.