Abstract The importance of temperature sensors has notably increased in recent years, paralleling the surge in demand for flexible and stretchable sensor technologies. In this study, we fabricate and characterize a flexible resistive temperature sensor based on Laser-Induced Graphene (LIG) on Polyetherimide (PEI). The structure and morphology of LIG are thoughtfully characterized proving the formation of a graphitic-based structure. Subsequently, the sensors were evaluated in terms of their temperature response, impact of relative humidity (RH), and bending cycles. The results reveal that the PEI-LIG flexible thermistor exhibits a high sensitivity of -0.159%/°C, with minimal influence from humidity. These findings contribute to advancing the research in inexpensive flexible temperature sensing technology, providing insights into material selection and sensor design for diverse applications.