It is of practical significance to develop gas sensors with high sensitivity and high selectivity. In this study, ZnO nanoflakes were synthesized by hydrothermal synthesis, and Au/ZnO, Pd/ZnO, and Pt/ZnO nanoflakes were fabricated by uniformly loading small-sized Au, Pd, and Pt nanoparticles using an ultraviolet-assisted reduction. Gas-sensing performance tests revealed that Au/ZnO nanoflakes exhibited a higher response to isopropanol compared to Pd/ZnO, Pt/ZnO, and ZnO nanoflake sensors. At the working temperature of 225 °C, it demonstrated response of 132.2 to 100 ppm isopropanol, with 8 s response time and 12 s recovery time, and showed high selectivity, repeatability, and stability. Hydrogen sensing performance of Au/ZnO nanoflakes was also evaluated at the optimal operating temperature, yielding a response of 13.5 to 100 ppm hydrogen, with response time and recovery time of 17 and 21 s, respectively, and exhibiting a high concentration-dependent response. The material’s enhanced gas sensing performance is due to a synergistic effect. This effect combines abundant active sites on nanoflakes with inherent catalytic properties of gold nanoparticles.