Au nanoparticle (Au NP) modified α-Fe₂O₃ nanodisk structures are obtained using a facile hydrothermal method and annealing based surface treatment. XRD, EDS, SEM, TEM and XPS are used to characterize the as-prepared samples, showing crystalline structured Au NPs of about 6–16 nm in diameter on the surface of α-Fe₂O₃ nanodisk structures of about 145 ± 15 nm in diameter. The Au NP modified α-Fe₂O₃ nanodisk structures are then investigated for acetone detection under different operating temperatures, showing improved gas sensing performance compared to the pure α-Fe₂O₃ nanomaterial. In particular, under the optimum working temperature (275 °C), the sensor response of Au_0.5Fe can reach a sensibility of 19.5 toward 100 ppm acetone, which is about two times higher than that of the pure one. Meanwhile, the Au_0.5Fe acetone sensor also exhibits fast response and recovery time (4 s/7 s), good linear relationship (50–5000 ppb), low detection limit (50 ppb), excellent long-term stability and superior selectivity. Finally, the enhanced gas sensing mechanism of Au NP modified α-Fe₂O₃ nanomaterials can be attributed to the combined action of chemical and electronic sensitization of Au NPs, which are promising as highly sensing materials toward acetone detection.