The creation of sustainable nanomaterials from renewable biomass has become a focal point in environmental nanotechnology due to their afordability, widespread availability, adjustable surface properties, and potential use in environmental and biological contexts. In this regard, coconut shell—a common lignocellulosic agricultural byproduct—emerges as a promising source for producing nanobiochar. Thismaterialisgeneratedbybreakingdownbiochartothenanoscale,whichenhances its specifc surface area, porosity, surface functionality, adsorption capacity, and catalytic activity compared to traditional biochar. Such attributes make nanobiochar a viable candidate for antimicrobial uses. The rising issue of antimicrobial resistance has created an urgent demand for alternative and eco-friendly antimicrobial agents that can efectively manage pathogenic and multidrug-resistant microorganisms. Nanobiochar can engage with microbial cells via surface adsorption, electrostatic interactions, membrane disruption, and reactive surface functionalities, efectively inhibiting bacterial proliferation and bioflm development. Waterborne pathogens, especially Escherichia coli, pose signifcant environmental and public health risks due to their link to gastrointestinal and systemic infections. Thus, nanobiochar derived from coconut shells holds promise as a sustainable antibacterial solution for water treatmentandvariousenvironmentalapplications.Thisreviewcoverstheproduction, physicochemical properties, antibacterial mechanisms, and environmental uses of biochar and nanobiochar, with a particular focus on those derived from coconut shells. This reviewalso emphasizes the potential of nanobiochar to mitigate microbial contamination while facilitating the valorization of agricultural waste. Future investigations should aim to refne synthesis methods, clarify antibacterial mechanisms, evaluate environmental safety, and assess the long-term efcacy of nanobiochar in practical applications.