This study is focused on the growth of graphene doped ZnO (ZnO:Gr) nanocomposite thin films by a thermionic vacuum arc (TVA) technique. ZnO:Gr nanocomposite thin films were deposited onto glass and silicon (Si) substrates. The influence of the dopant effect on structural, optical, morphological properties of the ZnO:Gr nanocomposite thin films were investigated by using various analysis techniques such as interferometer, UV-Visible spectrophotometer, X-ray diffraction (XRD), Raman spectrometer, Fourier Transform Infrared spectroscopy (FTIR), Photoluminescence (PL) spectroscopy, Field Emission Scanning Electron Microscopy (FESEM), and Atomic Force Microscopy (AFM). Thickness values of the ZnO:Gr nanocomposite thin films for the deposited layers onto glass and Si substrates were measured as to be 50 nm and 20 nm, respectively. In XRD patterns, the reflections of the ZnO and carbon nanostructures were observed. Using UV-Vis spectrophotometer and optical interferometer, the refractive index, reflectance, transmittance, absorbance and optical band gap graphs of the ZnO:Gr nanocomposite thin films were determined. Optical band gap of the ZnO:Gr nanocomposite thin film that deposited on glass substrate was determined as to be 3.15 eV via optical method and the result is in good harmony with PL measurement. PL spectrum showed an ultraviolet (UV) emission peak at 397 nm (3.12 eV). From the Raman analysis of the ZnO:Gr nanocomposite thin films, ZnO, D and 2D peaks of the graphene were observed. FTIR spectroscopy was used to analyze the chemical composition of the samples. According to AFM and FESEM analysis, ZnO:Gr nanocomposite thin films are smooth, flat, granular, uniform and dense form. Due to the larger crystallite sizes ZnO:Gr nanocomposite thin film onto Si substrate has lower resistivity according to the ZnO:Gr nanocomposite thin film deposited onto glass substrate. As a result, ZnO:Gr nanocomposite thin films are promising material for potential applications as to be a transparent conducting oxide (TCO) material.