A non-volatile memory integrated circuit device and a method of fabricating the same are disclosed. The non-volatile memory integrated circuit device includes a semiconductor substrate, a tunneling dielectric layer, a memory gate and a select gate, a floating junction region, a bit line junction region and a common source region, and a tunneling-prevention dielectric layer pattern. The tunneling dielectric layer is formed on the semiconductor substrate. The memory gate and a select gate are formed on the tunneling dielectric layer to be spaced apart from each other. The floating junction region is formed within the semiconductor substrate between the memory gate and the select gate, the bit line junction region is formed opposite the floating junction region with respect to the memory gate, and a common source region is formed opposite the floating junction region with respect to the select gate. The tunneling-prevention dielectric layer pattern is interposed between the semiconductor substrate and the tunneling dielectric layer, and is configured to overlap part of the memory gate.