A thin film transistor array substrate capable of reducing degradation of a device due to degradation of an oxide semiconductor pattern and a method of fabricating the same are provided. The thin film transistor array substrate may include an insulating substrate on which a gate electrode is formed, a gate insulating film formed on the insulating substrate, an oxide semiconductor pattern disposed on the gate insulating film, an anti-etching pattern formed on the oxide semiconductor pattern, and a source electrode and a drain electrode formed on the anti-etching pattern. The oxide semiconductor pattern may include an edge portion positioned between the source electrode and the drain electrode, and the edge portion may include at least one conductive region and at least one non-conductive region.