Abstract The current research work emphases on analysing the characteristics of combustion, performance, and emissions of Polanga Biodiesel (PBD) fuelled single-cylinder diesel engine with Al2O3 nano-additives added at a concentration of 25 ppm and 50 ppm. The results were compared with the baseline diesel fuel at varying engine loads (25%, 50%, 75% and 100%) in agriculture-based single-cylinder diesel engine of 17.5 Compression ratio at a constant engine speed of 1500 rpm. Al2O3 nano-additives were blended with PBD using magnetic stirrer and ultrasonicator. Experimentation results revealed that the addition of the nanoparticles in PBD improved the combustion and emission characteristics of base fuel due to higher surface area to volume ratio of nano-additives. Moreover, Al2O3 nanoparticles addition enhanced the brake thermal efficiency (BTE) and lowered the brake specific fuel consumption (BSFC) by 6.58% and 7.38% respectively. Subsequently, the emissions of HC, CO, NOx and smoke opacity were improved with the addition of fuel borne additives in PBD owing to improved combustion efficiency. PBD + 25 ppm Al2O3 resulted in lowest ignition delay (ID) while PBD + 50 ppm Al2O3 resulted in the highest mass fraction burnt (MFB). In the case of particle size diameter (PSD) analysis, lowest size particulates were recorded for PBD + 25 ppm Al2O3 throughout the engine load conditions. Overall, PBD + 50 ppm Al2O3 nano additives are best compared to improved combustion and minimized emissions.