threat of depletion of fossil fuels, extensively used in transport sector, is promoting the research in the field of alternative fuels. Biofuels possess properties close to that of diesel, but being viscous, used as blend with diesel in compression ignition (CI) engines. The current work explores the mixing of two biofuels, karanja oil and rice bran oil, in diesel (designated as RK20) and to observe the performance of CI engine. The blend was made by mixing the oils in the proportion of 10:10:80 (karanja oil, rice bran oil and neat diesel (ND), respectively). The test rig used to conduct the investigation was a double-cylinder, turbocharged and water-cooled direct injection CI engine having constant speed of 1800 rpm and fixed compression ratio of 18.5:1. The injection parameters were varied to optimize the performance parameters of CI engine for the prepared blend of biofuel. The optimized output parameters were brake specific fuel consumption (BSFC) and brake power (BP) of the CI engine. The ranges of injection timing (IT) and injection pressure (IP) were 15∘–28∘btdc and 230–300 bar, respectively. Central composite design technique of response surface methodology was used for design of experiments. The results include the lowest BSFC at low IP and IT for both ND and RK20 blend, also comparable with each other. Maximum BP and minimum BSFC were predicted at 15∘btdc and 230 bar IT and IP respectively for both RK20 blend and ND.