A p-side-up GaN/Ag/Au-Sn/Si light-emitting diode (LED) has been fabricated by a combination of laser lift-off and wafer-transfer techniques. The Ag/Au-Sn mirror structure was chosen to favor high optical reflectivity, low contact resistance with n-GaN, vertical conducting, and low-temperature (∼300°C) wafer bonding. The GaN/Ag/Au-Sn/Si LED presented a maximum luminance intensity of 129 mod (@ 20 mA) with a forward voltage of 3.3 V. The luminance intensity is over two times in magnitude as compared with that of the original planar GaN/sapphire LED. Under high current injection, the GaN/Ag/Au-Sn/Si LED also showed a more stable emission wavelength. This feature is attributed to the Si substrate providing a good heat sink.