A high-power chip structure of GaN/mirror/Cu light-emitting diodes (LEDs) was developed by a combination of laser lift-off and electroplating techniques. Especially, the LED samples can be accomplished without additional scribing or dicing process. The luminance intensity of the GaN/mirror/Cu LED is about 50% higher than that of the original GaN/sapphire sample. The output power of the GaN/mirror/Cu LED increases linearly with injection current up to 180 mA, while early saturation of the GaN/sapphire device occurs at 70 mA. These indicate that the joule heating is less pronounced for the GaN/mirror/Cu LED sample where the metallic substrate provides a good heat sink.