In the present study, steam injection method is implemented to a hydrogen-enriched Diesel engine in order to improve the levels of performance and NO emissions. As hydrogen enrichment method increases effective efficiency, NO emissions could be increased. However, the steam injection method is used to control NO emissions and improve the engine performance. Due to these positive effects, hydrogen enrichment and the steam injection method are applied into a Diesel engine by using a two-zone combustion model for 30% hydrogen enrichment of the fuel volume and 20% steam ratio of the fuel mass at full load conditions. The results obtained are compared with conventional Diesel engine, steam injected Diesel engine, hydrogen-enriched Diesel engine, and hydrogen-enriched Diesel engine with steam injection in terms of performance and NO emissions. In the results, the effective efficiency and effective power improve up to 22.8% and 3.1%, as NO emissions decrease up to 22.1%. Hence, the hydrogen enrichment with steam injection method is more environmentally friendly with better performance.