In this study, the effects of thermal annealing on RF-coated GZO thin films on n-Si and PET substrates at room temperature at 200 W RF power were investigated systematically. Deposited film on the n-Si substrate was annealed at range of 100 - 600 degrees C for 1 hour in air at atmospheric pressure with CTA. UV-Vis measurements of flexible films prepared at 100 and 200 degrees C were evaluated due to the deterioration of the PET substrate form at 300 degrees C temperature. The energy band gaps of the films were found as 3.10 and 3.30 eV, respectively. It was revealed from the XRD results that GZO films grown on Si have c-oriented hexagonal wurtzite structure. UV sensor fabrication was performed from the flexible GZO film annealed at 200 degrees C with the highest band gap energy. The UV-light sensitivity of the produced sensor was determined by I-V measurements in light (lambda = 365 nm) and dark conditions. Photo-sensitivity of the flexible sensor was found to be 8.07 at 2V.