Blue/near-UV light-emitting diodes composed of position controlled n-ZnO nanowires arrays and a p-GaN thin film substrate are demonstrated. Under forward bias, each single nanowire is a light emitter. By Gaussian deconvolution of the emission spectrum, the origins of the blue/near-UV emission are assigned specifically to three distinct electron-hole recombination processes. The LEDs give an external quantum efficiency of 2.5%.