The efficient management of environmental pollution caused by fossil fuel combustion in internal combustion engines (ICE) remains a significant challenge. This study investigates the potential of soybean methyl ester, a biodiesel, as an alternative fuel for a four-stroke, four-cylinder diesel engine. Biodiesel was produced via the transesterification of soybean oil and blended with regular diesel fuel in volume ratios of 2% (B2), 5% (B5), and 10% (B10). The emission characteristics of the engine operating on these blends were analyzed and compared to those using regular diesel fuel. A portable Autoplus Automotive exhaust gas analyzer was employed to measure emissions of total nitrogen oxides (NOx), carbon dioxide (CO2) and carbon monoxide (CO). Results indicated that CO2 emissions were reduced by 8%, 8%, and 20%, and CO emissions decreased by 5.89%, 11.76%, and 35.3% for B2, B5, and B10 blends, respectively, compared to diesel. However, NOx emissions for B2, B5, and B10 were found to be 0.83%, 1.24%, and 1.84% higher than those of regular diesel. These findings demonstrate the potential of soybean biodiesel to mitigate CO and CO2 emissions while highlighting the need to address increased NOx emissions.