The analyses of energetic and exergetic performance parameters along with the sustainability index and exergetic performance coefficient of internal combustion engines have been a vital subject to figure out for evaluating an alternating fuel candidate to being replaced traditional diesel fuel because these analyses are known as indicators for showing both quantity and quality for the energy sources. In this context, this work deals with the exergy and energy analyses of a four-stroke, single-cylinder, direct-injection, compression-ignition (CI) engine has been assessed when the tested engine powered by the peanut oil biodiesel (POB) and conventional diesel fuel at various engine loads (from 25% to 100%) with constant engine speed (1500 rpm). The findings of the research coming from the aforementioned analyses exhibited that the engine consumed more biodiesel fuel owing to the lesser energy content to maintain the power output as the same for the test fuels. The analyses depicted that the energy and exergy efficiency results ascended with the augmentation of the load. M 100% load operating condition, the highest energy efficiencies for diesel fuel and biodiesel were calculated to be as 39.43% and 35.11%, respectively, while the corresponding exergetic efficiencies were obtained to be as 36.99% and 32.63%, respectively. Because of the increasing engine load resulting in decreasing thermodynamic irreversibilities, the destruction of exergy along with the generation of entropy increased associated with the turn up in load. The lowest destructed exergy values revealed at the load of 100% for test fuels with the outcomes of 49.05% and 52.73% for diesel fuel and biodiesel, respectively. The peak sustainability indexes were 1.48 and 1.59 for biodiesel and diesel fuel, respectively while the corresponding exergetic performance coefficients were calculated to be as 0.75 and 0.62, respectively. In conclusion, it could be indicated that the analyses result of the tested diesel engine running on POB were occurred to be reasonably close to that of the engine powered by conventional diesel fuel. Overall, POB can be evaluated as an alternative candidate for fossil-based diesel fuel.