Abstract: Although biopolymers have been widely utilized as triboelectric materials for the construction of self-powered sensing systems, the annihilation of triboelectric charges at high temperatures restricts the output signals and sensitivity of the assembled sensors. Herein, a novel chitosan/montmorillonite/lignin (CML) composite film was designed and employed as a tribopositive layer in the assembly of a self-powered sensing system for use under hot conditions (25–70°C). The dense contact surface resulting from the strong intermolecular interaction between biopolymers and nanofillers restrained the volatilization of induced electrons. The optimized CML-TENG delivered the highest open-circuit voltage (V_oc) of 262 V and maximum instantaneous output power of 429 mW/m². Pristine CH-TENG retained only 39% of its initial V_oc at 70°C, whereas the optimized CM₅L₃-TENG retained 66% of its initial V_oc. Our work provides a new strategy for suppressing the annihilation of triboelectric charges at high temperatures, thus boosting the development of self-powered sensing devices for application under hot conditions.