Due to the higher demand for renewable and sustainable energy sources, it is very important to investigate fuels such as soybean biodiesel. This study focuses on a compression ignition diesel engine’s performance characteristics and emissions when running on soybean biodiesel (B100 with 5% ethanol) in comparison to normal diesel fuel. The hypothesis is based on soybean being a biodiesel that can perform reasonably close to normal diesel engine with low emissions. Key performance variables such as indicated power, brake horse power, frictional power, thermal efficiencies, mechanical efficiency and specific fuel consumption were obtained during the experimental analysis as depicted in the research methodology. Emissions of CO, HC, CO₂, O₂, and NOₓ for the diesel fuel and for various biodiesel blends (B25, B50, B75) were also studied. Findings indicated that soybean biodiesel had comparative fuel economy and power generation as diesel, and CO emission was reduced by 40, while NOₓ emissions increased by 48 percent at full load condition. This studies clearly show that it is easy to use soybean oil based biodiesel as a renewable eco-friendly alternative biodiesel for compression ignition engines with much more improvement opportunities in terms of emissions performance. The originality of this work resides in the broader scope to evaluate the performance, emissions and trade-offs of soybean biodiesel blends and prospects that the literature on the sustainability of biodiesel is expanding by bringing in such new perspectives on it. Through the integration of experimental results, relevant performance as well as environmental assessments, this study extends previous endeavors and provides concrete recommendations for researchers, industry players and policy-makers willing to contribute to the advancement of alternative fuels.