Oxyhydrogen produced by water electrolysis is becoming an alternative fuel, due to it can reduce air pollution levels. Therefore, this work is to propose dual-fuel regular diesel combined with oxyhydrogen and exhaust gas recirculation (EGR), increased from 0.20 to 0.34 L/min and 5 to 15% respectively, while operated with a common-rail direct injection (CRDI) diesel engine at a constant speed under various powers. In cases of regular diesel combined with increasing oxyhydrogen, it led to an increase in engine performance. Carbon dioxide (CO2), carbon monoxide (CO), black smoke (BS), and particulate matter (PM) emissions reduced but nitric oxide (NO) emission increased with increasing oxyhydrogen. Remarkably, regular diesel combined with adding oxyhydrogen and EGR led to the improvements of engine performance and exhaust emissions. This work found the use of regular diesel combined with 0.34 L/min oxyhydrogen and 15% EGR decreasing the levels of CO2, CO, BS, and PM by 9.72%, 6.54%, 11.28%, and 8.72%, respectively. NO emission increased by only 2.04%.