The present disclosure relates to a polycrystalline diamond compact (PDC) cutter with protective barrier coating. The PDC cutter consists of an unleached or leached polycrystalline diamond (PCD) table, a cemented carbide body substrate, and a coating disposed on the cutter. The coating covers at least partially the exterior surfaces of the PCD table of the PDC cutter, and it may also extend over partially or entirely the exterior surfaces of the cemented carbide body. The coating is either a single layer or multilayer. The coating has a thickness of 0.4 μm-100 μm. The coating may have a strong metallurgical bonding with PDC cutter. The coating comprises an oxidation-resistant layer that protects the PDC cutter from thermal and mechanical degeneration during brazing and cutting applications. Methods for preparing such the coating comprise physical vapor deposition, chemical vapor deposition, thermoreactive deposition and diffusion, electrical plating, electroless plating, or their combinations.