Purpose – A new simple technique was developed to synthesize graphene film on flexible Poly- ethylene Terephthalate (PET) substrate and applied as a strain sensor. Design/methodology/approach – Graphene film was synthesized using Laser treatment of graphene oxide (GO) film deposited on PET substrate. A universal Laser system was used to simultaneously reduce and pattern the GO film into Laser Reduced Graphene Oxide (LRGO) film. Findings – The Laser treatment synthesizes a multilayer graphene film with overlapped flakes, which shows structure integrity, mechanical flexibility and electrical conductivity of 1.33 x 10 3 S/m. The developed LRGO/PET film was used to fabricate a high sensitivity strain sensor. The sensitivity and temperature dependency of its gauge factor (GF) was examined at applied strains up to 0.25% and operating temperatures up to 80 o C. The fabricated sensor shows stable GF of ~ 78 up to 60 o C with standard error of the mean not exceed ± 0.2. Originality/value – The proposed method offers a new simple and productive technique to fabricate large-scale graphene-based flexible devices at a low cost.