An electrochemical route for highly selective immobilization of a β-lactam family antibiotic, amoxicillin (AMX), from the other drugs, penicillin and ampicillin, on multiwalled carbon nanotube modified glassy carbon electrodes (GCE/AMX@MWNT), without any linkers and surface functionalization, has been successfully demonstrated. The electrochemical response of the AMX on GCE/MWNT showed an irreversible oxidation peak at 0.5 V vs. Ag/AgCl (A1), followed by the growth of a new redox peak at 0 V vs. Ag/AgCl (A2/C2) in pH 7 phosphate buffer solution, which is in parallel to a control phenol electrochemical response, revealed that the phenoxy radical electrogenerated at A1 gets subsequently adsorbed on the underlying MWNT modified electrode with a specific surface confined A2/C2 redox peak with proton-coupled electron transfer behaviour. Physicochemical characterization from X-ray diffraction, transmission electron microscopy and scanning electron microscopy collectively evidenced the immobilization of AMX both on the inner and outer (surface) walls of the carbon nanotubes. Further, the AMX@MWNT hybrid material was found to show enhanced antibacterial activity against three bacterial pathogens, Escherichia coli, Staphylococcus aureus and Bacillus subtilis, over the unmodified AMX and MWNT. Finally, as an environmental pollution remedy, the uptake of the AMX drug from five different simulated sources: river water, sea water, river soil, sea soil and farm milk, was successfully demonstrated by this new electrochemical methodology. © 2010 The Royal Society of Chemistry.