N-doped MWCNTs are widely used in energy storage devices, particularly in supercapacitors and lithium-ion batteries, due to their enhanced electrical conductivity and improved electrochemical performance. They serve as efficient electrode materials, providing higher capacitance and better charge-discharge cycles. In catalysis, N-doped MWCNTs are employed as supports for metal nanoparticles, enhancing catalytic activity and stability in reactions such as oxygen reduction, hydrogen evolution, and CO2 reduction. Their unique structure and nitrogen incorporation improve surface reactivity and selectivity. Additionally, they are utilized in environmental applications, including water purification and gas sensing. Their high surface area and nitrogen functional groups make them effective in adsorbing pollutants and detecting gases like ammonia and nitrogen oxides with high sensitivity. In biomedical fields, N-doped MWCNTs are explored for drug delivery and biosensing due to their biocompatibility and ability to functionalize with various biomolecules, enabling targeted therapy and precise detection of biological markers.