GaN-based light-emitting diode (LED) was successfully fabricated using surface plasmons (SPs) excited at the metal/semiconductor interface. Normally, SPs excited by the interaction between light and metal surfaces were known to enhance the internal quantum efficiency of LEDs via the quantum-wells (QWs) and SPs coupling. The penetration depth of SPs fringing field for the Ag film was calculated as 42.0 nm at an emission wavelength of 460 nm. Thus, the distance between the QWs and metal was critical for QWs-SP coupling. However, the p-GaN layer in blue emissive GaN-based LEDs, which is a sandwich layer between the active and p-type conducting layers, must has a thickness of over 120 nm to ensure the sufficient mobility of carriers. In this study, an Ag nanoparticle layer was coated on p-GaN top layer as the grating structure. The light extraction efficiency of lateral conducting blue LED is expected to be enhanced by the surface plasmon-TM light mode coupling during the localized surface plasmon resonance. Compared to the optoelectronic performance of the conventional LED, the SP-enhanced LED shows the superior performance, even though the silver nanoparticles were placed at least 200 nm away from the quantum-well active layer. The output power of the SP-enhanced LED exhibited over 1.1 times in magnitude as compared with that of the conventional LED at 350 mA, while still keeping nearly the same current-voltage characteristic.