Ozone gas sensors on flexible substrate with Ti/Pt interdigitated electrodes have been fabricated by standard photolithography and femtosecond laser ablation processes under the same conditions. ZnO nanoparticles deposited by drop coating method have been used as sensitive thin film material with 280 nm thickness due to their excellent characteristics on gas detection. The physical properties obtained by both processes have been studied and their critical effects on the gas sensitive response are discussed. It was found that although both samples present small dimensional variations, the samples fabricated by laser ablation shows a bigger sensitive response to ozone at 200 °C. However, both samples have been used as ozone gas sensor and present excellent sensing characteristics, giving good stability, fast response/recovery and excellent range of detection from 5 ppb to 300 ppb.