Biodiesel was produced using the transesterification method from waste sunflower and cotton oil. As a result of the analysis of the new type of nanoparticle-added biodiesel fuels we produce, the parameters with a decrease in emissions are CO, HC, and smoke emissions. There is a partial increase in NOx emissions. In addition, nanoparticle addition made a positive contribution by increasing thermal efficiency. The produced MgO nanoparticle-doped biodiesel fuel samples were compared with diesel fuel. As seen in these comparisons, nanoparticle additives contributed positively to reducing emission values. These improvements were observed as a 31.25 % reduction in CO in the WSOB5+ 100 ppm MgO fuel sample, 41.6 % reduction in HC in the COB5+ 100 ppm MgO fuel sample and 36.92 % reduction in smoke (soot) in COB5+ 100 ppm MgO fuel sample. A comparison was made between the fuel samples in our study, biodiesel produced from waste sunflower and cotton, and fuels produced with nanoparticle additives of 50, 75, and 100 ppm. It was observed that the most efficient fuel sample in terms of emission values and performance was COB5 + 100 ppm MgO nanoparticle additive fuel. The biodiesel fuel sample produced with COB5 + 100 ppm MgO nanoparticle additives provided a 3.25 % improvement in thermal efficiency compared to biodiesel without additives. A positive effect on the heat transfer coefficient was observed as a result of the data on the new type of nanoparticle doped biodiesel. With the impact of this contribution, parameters such as positive contribution to in-cylinder temperature, ignition delay, and combustion time were positively affected in the same direction. Another positive effect of nanoparticle additive to biodiesel, thermal efficiency, increased by 1.1 % in the COB5 + 100 ppm MgO fuel sample. Depending on the decrease in emission rate, it was concluded that the nanoparticle additive added to the fuel greatly benefits the environment.