This study presents an intelligent self-powered remote IoT fire warning system based on high-performance single-walled carbon nanotube (SWCNT)/titanium carbide (MXene) thermoelectric (TE) composite films. The flexible composite films, prepared by solution mixing, exhibit p-type characteristics with excellent high-temperature stability, flame retardancy, and TE performance (power factor of 239.7 ± 15.8 μW m⁻¹ K⁻²). The assembled TE devices (TEDs) achieve an ultrafast fire warning response time of ~0.1 s with a threshold voltage of 1 mV, rivaling many state-of-the-art systems. The TEDs demonstrate exceptional repeatability and long-term stability, even after 50 repeated cycles and 180 days of air exposure. A TED-based wireless intelligent fire warning system was developed by integrating an amplifier, analog-to-digital converter, and Bluetooth module. The system combines TE characteristics, high-temperature stability, and flame retardancy with wireless IoT signal transmission, making it promising for next-generation self-powered remote IoT fire warning applications. The composite films show excellent flame retardancy, with the formation of a TiO₂ flame-retardant layer through partial thermal oxidation of MXene and the exceptional thermal stability of SWCNT. The TEDs also exhibit high thermal stability, with a maximum weight loss temperature of 704 °C. The fire warning performance of the TEDs is highly dependent on the number of p–n couples, threshold voltage, and flame distance. The TED-10pn with a threshold voltage of 1 mV achieves an ultrafast trigger time of ~0.1 s at a flame distance of 0 cm, and ~1.9 s at 20 cm. The system demonstrates excellent durability, with the TED retaining the ability to trigger a warning response within 3 s even after 180 days of air exposure. The system is designed for building applications, with the TED embedded in building walls to conduct simulating flame tests. The system can detect fire hazards quickly and transmit warning signals remotely. The study highlights the potential of SWCNT/MXene TE composites for next-generation self-powered remote IoT fire warning applications.This study presents an intelligent self-powered remote IoT fire warning system based on high-performance single-walled carbon nanotube (SWCNT)/titanium carbide (MXene) thermoelectric (TE) composite films. The flexible composite films, prepared by solution mixing, exhibit p-type characteristics with excellent high-temperature stability, flame retardancy, and TE performance (power factor of 239.7 ± 15.8 μW m⁻¹ K⁻²). The assembled TE devices (TEDs) achieve an ultrafast fire warning response time of ~0.1 s with a threshold voltage of 1 mV, rivaling many state-of-the-art systems. The TEDs demonstrate exceptional repeatability and long-term stability, even after 50 repeated cycles and 180 days of air exposure. A TED-based wireless intelligent fire warning system was developed by integrating an amplifier, analog-to-digital converter, and Bluetooth module. The system combines TE characteristics, high-temperature stability, and flame retardancy with wireless IoT signal transmission, making it promising for next-generation self-powered remote IoT fire warning applications. The composite films show excellent flame retardancy, with the formation of a TiO₂ flame-retardant layer through partial thermal oxidation of MXene and the exceptional thermal stability of SWCNT. The TEDs also exhibit high thermal stability, with a maximum weight loss temperature of 704 °C. The fire warning performance of the TEDs is highly dependent on the number of p–n couples, threshold voltage, and flame distance. The TED-10pn with a threshold voltage of 1 mV achieves an ultrafast trigger time of ~0.1 s at a flame distance of 0 cm, and ~1.9 s at 20 cm. The system demonstrates excellent durability, with the TED retaining the ability to trigger a warning response within 3 s even after 180 days of air exposure. The system is designed for building applications, with the TED embedded in building walls to conduct simulating flame tests. The system can detect fire hazards quickly and transmit warning signals remotely. The study highlights the potential of SWCNT/MXene TE composites for next-generation self-powered remote IoT fire warning applications.