Disclosed are a light emitting device having a zener diode therein and a method of fabricating the light emitting device. The light emitting device comprises a P-type silicon substrate having a zener diode region and a light emitting diode region. A first N-type compound semiconductor layer is contacted to the zener diode region of the P-type silicon substrate to exhibit characteristics of a zener diode together with the P-type silicon substrate. Further, a second N-type compound semiconductor layer is positioned on the light emitting diode region of the P-type silicon substrate. The second N-type compound semiconductor layer is spaced apart from the first N-type compound semiconductor layer. Meanwhile, a P-type compound semiconductor layer is positioned on the second N-type compound semiconductor layer, and an active layer is interposed between the second N-type compound semiconductor layer and the P-type compound semiconductor layer.