An array substrate for a digital X-ray detector, a digital X-ray detector including the same, and a method for manufacturing the same are provided. A thin film transistor (TFT) array substrate for a digital X-ray detector includes: a base substrate, a thin film transistor over the base substrate, a lower electrode connected to the thin film transistor, a positive-intrinsic-negative (PIN) layer over the lower electrode, the PIN layer including: an N-type semiconductor layer, an intrinsic semiconductor layer, and a P-type semiconductor layer, a bias electrode over the PIN layer, and an upper electrode covering the PIN layer and the bias electrode.