An ever-increasing drift of energy consumption, unequal geographical distribution of natural wealth and the quest for low carbon fuel for a cleaner environment are sparking the production and use of biodiesels in many countries around the globe. In this work, jatropha and karanja biodiesels were produced from the respective crude vegetable oils through transesterification, and the different physical properties of the produced biodiesels have been presented and found to be acceptable according to the ASTM biodiesel specification standard. This paper presents the experimental results of the research carried out to evaluate the BTH, BSFC exhaust emission characteristics of jatropha and karanja blends in a single-cylinder diesel engine at different engine load. Comparative measures of brake thermal efficiency, smoke opacity, HC, CO, and NOx have been presented and discussed. Engine performance, in terms of higher brake thermal efficiency and lower emissions (HC, CO, NOx) with jatropha-based biodiesel (JB50) operation, were observed compared to karanja-based biodiesel (KB50).