Thermal management of light-emitting diodes (LEDs) significantly reduces the chances of failure due to overheating and provides a better lifespan. The most efficient, compact, and low-cost cooling system must be developed for better heat dissipation. Researchers have conducted major investigations on LED performance for low-wattage applications. The current work focuses on the high-wattage real-life application of LEDs. Researchers have considered investigations for 100 W, 200 W, and 400 W capacity high-wattage LEDs in street, stadium, and high-mast tower applications. Copper-made, cylindrical, two-layered heat pipe with screen mesh wick has been designed and fabricated to cool LEDs. Dispersed copper and silicon oxide nanoparticles in distilled water are used as a working medium in a heat pipe. Types of working medium, filling ratio, and LED capacities were considered input variables during the experiment. The resultant variables are the evaporator and condenser temperature difference, thermal resistance, energy consumption, effective thermal conductivity, and overall heat transfer coefficient. Researchers have developed a dedicated experimental setup for testing, with all required measuring and controlling devices. A superior performance was observed with the Cu/DI water-filled heat pipe, considering a 60% filling ratio in the tested LEDs. Cu/DI water with a 60% filling ratio has a 15.2% and 3.5% lower temperature difference, contrasting with DI water and SiO2/DI water for 100 W LED.