The growing need to reduce emissions and improve efficiency in compression-ignition (CI) engines has accelerated research into hydrogen-assisted biodiesel combustion. The purpose of this study is to experimentally evaluate the effects of hydrogen enrichment on the performance, combustion, and emission characteristics of a CI engine fueled with corn oil methyl ester (COME20). The experimental investigation was conducted on a single-cylinder, four-stroke, water-cooled, direct-injection CI engine operating at a constant speed. Hydrogen was inducted through the intake manifold at volumetric enrichment ratios of 13.32%, 19.98%, and 26.64%, while neat diesel operation served as the reference condition. Engine performance parameters, in-cylinder combustion characteristics, and exhaust emissions were measured over a wide range of engine loads. The results show that hydrogen enrichment significantly enhances combustion efficiency and engine performance. The highest hydrogen enrichment level (26.64% H2-COME20) resulted in the highest brake thermal efficiency (40.77%) and the lowest brake-specific fuel consumption compared to neat diesel. Hydrogen addition substantially reduced carbon monoxide and hydrocarbon emissions due to improved oxidation, while nitrogen oxides increased because of higher in-cylinder temperatures. Combustion analysis revealed increased peak cylinder pressure, higher heat-release rates, and shorter ignition delay as the hydrogen fraction increased. In conclusion, hydrogen-enriched COME20 fuels offer a practical and effective approach to improving efficiency and reducing carbon-based emissions in existing CI engines, providing a promising near-term pathway toward cleaner, more sustainable engine technologies.