Today, there are environmental problems all over the world due to the emission of greenhouse gasses caused by the combustion of diesel fuel. The excessive consumption and drastic reduction of fossil fuels have prompted the leaders of various countries, including Iran, to put the use of alternative and clean energy sources on the agenda. In recent years, the use of biofuels and the addition of nanoparticles to diesel fuel have reduced pollutant emissions, improved the environment and enhanced the physicochemical properties of the fuel. The current research deals with the experimental evaluation of emissions and performance of a diesel engine running on graphene nanopowder together with diesel-biodiesel-ethanol blends. The engine variables studied included the engine speed (in three stages: 1800, 2200 and 2600 rpm) and three types of fuel including graphene nanoparticles (with values of 25 and 50 ppm), biodiesel (with volume percentages of 4, 6 and 8) and ethanol (with volume percentages of 2 and 4). The results showed that the power and torque of the D86 + B8 + E6 + G50 fuel increased on average by 20.26% and 28.76% at all engine speeds compared to the D100 fuel. The use of D86 + B8 + E6 + G50 fuel resulted in a significant reduction in CO (38.84%), UHC (21.24%) and NOx (19.92%) emissions compared to D100 fuel. In addition, a significant increase in CO2 emissions (23.19%) was observed. The results of this study clearly show that the use of biofuels and the addition of nanopowder to D100 fuel is a very effective method to improve combustion, performance and emission characteristics in diesel engines.