In this study, undoped and different concentrations (3%, 6%, and 9%) of chromium-doped ZnO thin films were deposited using the ultrasonic spray pyrolysis technique, and the significant effects of the dopant concentration on the physical properties of the deposited films, including structural, morphological, and electrical characteristics, were investigated. The structural analysis revealed that the thin films possessed a hexagonal wurtzite structure, and the intensity of the peak corresponding to the (002) plane initially increased with the increasing dopant concentration, then decreased, and increased again. Morphological analysis showed that there were no regular changes in the crystal sizes with increasing dopant concentration, but noticeable alterations occurred on the film surfaces. The optical band gaps of the deposited films increased from 3.24 eV to 3.31 eV with the increasing dopant concentration. The electrical resistivity values of the films varied between 3.04x101 Ωcm and 3.35x106 Ωcm, indicating that higher dopant concentrations led to an increase in resistivity