Presented herein is an optically transparent glass-fabric-reinforced hybrimer film (350-GFRHybrimer film) featuring a low coefficient of thermal expansion (12–14 ppm/°C) and high-temperature processability (350°C). The 350-GFRHybrimer film was fabricated with glass-woven fabrics as reinforcement, and a highly thermally stable siloxane hybrid resin as a matrix. To confirm the potential of the 350-GFRHybrimer film as a flexible substrate, 350°C-processed oxide thin film transistor arrays are demonstrated on the 350-GFRHybrimer film.