Diesel engines pollutants are harmful to humans and cause issues like acid rain and photochemical smog, leading to strict environmental regulations. Improving diesel engine performance is crucial, given the rapid depletion of fossil fuel resources and the harmful emissions. To meet stringent global emission standards, research focuses on reducing emissions through new fuel formulations, engine design modifications, and exhaust gas treatments. In this work evaluate the performance and emission characteristics of the diesel engine using various concentrations of MWCNT (10 ppm, 20 ppm, 30 ppm, 40 ppm, 50 ppm and 60 ppm) blend with diesel and pure diesel under different loads. The reformulated diesel fuel with Multiwalled Carbon Nanotubes reduces fuel consumption and harmful emissions without altering key physiochemical properties. This blend enhances combustion and results in a shorter ignition delay period.