Anaerobic digestion (AD) of livestock waste is a sustainable pathway for renewable energy production, yet methane yield is often limited by the slow hydrolysis of lignocellulosic material. Pretreatment methods have been proposed, but many are costly or environmentally burdensome. This study investigates ultraviolet light irradiation as a novel, low-energy pretreatment to enhance methane production from cow dung. Fresh cow dung was exposed to UV light at 254 nm and intensity and for 0 (control), 30, 60, 90, 120, 150, and 180 minutes before undergoing 35-day anaerobic digestion at 37 °C. Methane yield and chemical oxygen demand (COD) removal were monitored. Results revealed a significant effect of UV exposure duration on both methane yield (p < 0.05) and COD removal (p < 0.05). Optimal performance occurred at 120 minutes (methane yield: 126 ± 28.3 mL/day; COD removal: 58.9%), representing a more than twofold improvement compared to the control. Overexposure (≥150 minutes) decreased methane yield and COD removal, likely due to the generation of inhibitory by-products. These findings suggest that UV light pretreatment, when optimised, can partially overcome hydrolysis limitations in AD. However, the study did not assess microbial dynamics, chemical intermediates, or scale-up feasibility, which remain critical gaps for future research.