Self-powered sensors are crucial in the field of wearable devices and the Internet of Things (IoT). In this paper, an organ-like Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub> MXene/metal-organic framework-derived copper oxide (CuO) gas sensor was powered by a triboelectric nanogenerator (TENG) based on latex and polytetrafluoroethylene for the detection of ammonia (NH<sub>3</sub>) at room temperature. The peak-to-peak value of open-circuit voltage and short-circuit current generated by the prepared TENG can reach up to 810 V and 34 μA, respectively. The TENG can support a maximum peak power density of 10.84 W·m<sup>-2</sup> and light at least 480 LEDs. Moreover, a flexible TENG under a single-electrode working mode was demonstrated for human movement stimulation, which exhibits great potential in wearable devices. The self-powered NH<sub>3</sub> sensor driven by TENG has an excellent response (<i>V</i><sub>g</sub>/<i>V</i><sub>a</sub> = 24.8 @ 100 ppm) at room temperature and exhibits a great potential in monitoring pork quality. Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub> MXene and CuO were characterized by SEM, TEM, EDS, XRD, and XPS to analyze the properties of the materials. The NH<sub>3</sub> sensing performance of the self-powered sensor based on MXene/CuO was greatly improved, and the mechanism of the enhanced sensing properties was systematically discussed.