In this study, composite electroplating technique is used to fabricate the diamond-added copper heat spreader for UV LED applications. Thermal dissipation characteristic and optical performance are improved as the composite diamond-added copper heat spreader adoption. The low thermal resistance of 18.4 K/W with UV LED using diamond-added copper heat spreader was measured. Surface temperature of UV LED using the diamond-added copper heat spreader is 50.42 °C at 500 mA injecting current lower than pure copper heat spreader of 59.9 °C and original heat spreader of 90.4 °C. The thermal diffusivity of the diamond-added copper is 0.7179 cm2/s measurement by laser flash method Output power and power efficiency of UV LEDs are also enhanced to 71.81 mW and 4.32 %, respectively, at 400 mA injection current. The optimal structure design and materials fabrication will be discussed.