This research focuses on biodiesel production from Gulmohar seeds using the transesterification method, with methanol as a catalyst at a 75% yield of Gulmohar oil biodiesel. Further, the biodiesel mixed with diesel at various blend ratios such as B20, B30, B40 and B50 and physicochemical characteristics are examined. The experimental investigation of performance and emission characteristics on single cylinder diesel engine using gulmohar biodiesel and diesel blends and compare the results with those from diesel. According to the findings, B20 blend emission characteristics and performance are very similar to the diesel fuel trend. Under full load, the Brake Specific Fuel Consumption (0.305 kg/kW.h) and Brake thermal efficiency (26.02%) for the B20 blend, which is closer to diesel and variations are 4.81% and 8.1%, respectively. Throughout the experiment, HC, CO, and smoke emission parameters were either less or equal for gulmohar biodiesel and its blends compared to diesel. However, the NOx emission of the biodiesel blends is 2 to 12% higher than diesel, but B20 has a 2.35% higher and lowest value among all the other blends. In addition, a central composite design (CCD) model using Response Surface Methodology (RSM) will be created, and the outcomes of a Compression Ignition (CI) engine will be optimized. Both analyses concluded that B20 is the most optimal blend among other blends and serves as a substitute for diesel.