Abstract: Fire accidents pose a significant threat to public safety, property, and the environment. Traditional power-dependent rescue and sensing devices are susceptible to failure or even explosion in high-temperature and open-fire environments. This research has developed fire-retardant cellulosic triboelectric materials, offering a potential solution. Due to the protection of hydroxyapatite, the cellulose nanofibril (CNF)/hydroxyapatite composite film did not undergo obvious deformation or carbonization after burning for 60 s under a 500 °C alcohol lamp flame. The closely packed cross-sectional structure facilitated air filling, endowing it with certain heat insulation performance. The high surface roughness and special microstructure greatly enhanced the triboelectric performance, achieving an open circuit voltage of 102 V and a short circuit current of 6.18 μA under a working area of only 4 cm2, surpassing most cellulose-based triboelectric materials. The results in self-powered sensing of high-temperature and open flames indicate that fire-retardant cellulosic triboelectric materials have the potential for use in high-temperature environments. This study introduces a new idea for energy harvesting and sensing at extreme conditions, which has important significance for the development of wearable self-powered sensors and the smooth progress of fire rescue operations.