In this work, single-crystalline copper telluride Cu_2-xTe (0 ≤ x ≤ 1) nanowires were synthesized on a copper substrate using a one-step, catalyst-free chemical vapor deposition method without a reducing agent. The produced nanowires had a uniform diameter of 226.2 ± 12.0 nm with a mean length of 13.89 ± 1.02 µm. X-ray diffraction pattern analysis using the Rietveld refinement revealed a composite phase composition comprising three distinct phases of mass fraction as follows: hexagonal Cu₂Te (81.50 ± 6.47%), orthorhombic CuTe (17.31 ± 7.59%), and cubic Cu₂O (1.18 ± 1.72%). X-ray photoelectron spectroscopy found evidence of the presence of both Cu²⁺ and Cu⁺ oxidation states of Cu. Moreover, the influence of Cu substrate thickness was investigated under the same experimental conditions. The thickness of the Cu substrate significantly impacted the copper telluride nanostructures’ morphology. When the Cu substrate thickness increased by ten, structures such as 1D nanowires, 2D hexagon sheets, and 3D dendrites became evident. UV–visible absorption studies showed that as Cu thickness increased from 0.15 mm to 1.5 mm, the absorption peak shifted from 533 nm to 614.70 nm. The detailed growth mechanisms of the 1D nanowires, 2D sheets, and 3D dendrites were discussed. Finally, the electrochemical performance of the produced nanostructured electrodes was evaluated using a three-electrode configuration, demonstrating superior electrochemical performance as a viable electrode material for electrochemical supercapacitors.