The present research work evaluated the combustion, performance, and emission characteristics of a Mahindra Jeeto single-cylinder, four-stroke diesel engine operated with third generation biodiesel blend, B20 (20% biodiesel and 80% diesel), obtained from three different algal species, Spirulina (B1), Chlorella Protothecoides (B2), and S. Marginatum (B3). The results of different algal biodiesel blends are numerically analyzed and compared vis-a-vis diesel fuel. The numerical evaluation was carried out using Diesel-RK software, a thermodynamic full-cycle engine analysis tool. The diesel engine was operated at six loads (5, 10, 15, 20, 25, 30 N-m) and a constant 1800 rpm speed. The findings showed that mixing 20% of Spirulina biodiesel in diesel fuel resulted in a 5.76% and 2.43% increase in maximum in-cylinder pressure and maximum in-cylinder temperature, respectively, about diesel. However, a 20% blend of S. Marginatum biodiesel showed enhancement in the performance characteristics as brake thermal efficiency increased by 0.64%, which resulted in a 4.56% decrease in brake-specific fuel consumption. Further, the B3 blend also improved the emission characteristics, that is 27.16% reduction in Bosch Smoke Number and a 6.80% reduction in carbon dioxide emissions.