Reactive co-sputtering technique has been used to fabricate pure zinc oxide and nickel doped zinc oxide thin films on glass substrate at room temperature 30º C. The actual target of this experimental work was to investigate the effect of nickel incorporation on structural and optical properties of nickel doped zinc oxide thin films. The deposited samples were characterized by using Energy-Dispersive Analysis X-ray, X-Ray Diffractometer, Atomic Force Microscope, Fourier Transform Infrared Spectroscopy and Ultraviolet-visible spectrophotometer to investigate the doping growth, structural crystallinity, surface morphology, chemical bonding information and optical properties. Scanning electron microscope has been used to measure the thickness of all deposited films. The X-Ray Diffractometer study of all deposited films reveals that the highly intensive peak has been found near glancing angle at 34.48º corresponds to miller indices (002), which confirmed the wurtzite hexagonal crystallite structure of zinc oxide that matched with JCPDS card no 36-1451. Crystallite size of deposited thin films is increased from 8 nm to 15 nm with the increasing of atomic % of nickel from 0 to 7.5 respectively in zinc oxide. The Fourier Transform Infrared Spectroscopy peak found at 432 cm-1 confirmed the deposited films are zinc oxide thin films. Optical band gap energy decreases from 3.15 eV to 2.21 eV where as the Urbach energy increases from 118meV to 243meVwith increasing of atomic % of nickel from 0 to 7.5 respectively.