Cu wires (CuWs) are widely used as electric transmission lines. However, their limited thermal and chemical stabilities become challenges under the high-power and harsh environment. Graphene is regarded as an ideal protective barrier for CuW benefiting from its impermeability to all atoms and molecules. Particularly, the excellent hydrophobicity of vertical graphene (VG) will strengthen its protective capability as a corrosion and oxidation barrier. Herein, VG is directly synthesized on CuW by plasma-enhanced chemical vapor deposition method. The hydrophobic VG coating with a high water contact angle can effectively exclude the corrosive liquid and moisture from CuW surface and prevent their further penetration. Consequently, the electrochemical corrosion rate of VG-CuW is reduced by ~ 13, 8, and 2 times, compared with bare CuW, VG-CuW with hydrophilic treatment, and CuW coated with thick horizontal graphene layers, respectively. Negligible oxidation occurs on VG-CuW after the long-time exposure to humid air at ~ 200 °C along with the largely enhanced tolerance under high-current operating condition. This study reveals the impressive potentials of hydrophobic VG as a robust corrosion and oxidation barrier for metal wires used in high-power cables and electronic devices in harsh environment.