Pharmaceutical contaminants are becoming increasingly prevalent in aquatic environments, posing a growing threat to human health, marine life, and ecosystem stability. Their persistence, resistance to natural degradation, and potential to bioaccumulate make them difficult to eliminate through conventional water treatment processes. To address this issue, the development of effective, low-cost, and environmentally sustainable treatment technologies has become a research priority. In this context, argan nut shells, an abundant agricultural by-product in Morocco, were utilised as a precursor for the synthesis of potassium hydroxide (KOH)-activated biochar for advanced water and wastewater treatment. The materials were synthesised by impregnating the biomass with KOH, followed by pyrolysis under a nitrogen (N₂) atmosphere at varying temperatures (500–1000 °C) with a controlled heating rate of 10 °C min^-1. The resulting materials were characterised using FTIR, TGA, SEM, XRD, and Raman spectroscopy to evaluate their structural, morphological, and surface properties. Their performance was investigated through a dual approach: (i) adsorption and (ii) electrocatalytic degradation of pharmaceutical pollutants using modified electrodes. Key operational parameters, including contact time, initial concentration, pH, and ionic strength, were optimised to possess the mechanism of conducting the adsorption and oxidative degradation. Among the prepared materials, those prepared at 900 °C exhibited outstanding performance, achieving a degradation efficiency. This might be attributed to their unique structural characteristics and enhanced surface properties, including favourable functional groups that promote both adsorption and catalytic activity. Overall, this study highlights the potential of argan nut shells as a sustainable precursor for high-performance carbon-based materials for advanced water treatment contaminated with pharmaceutical compounds.