Ethylene is a crucial raw material for the production of chemical products, and thus, the development of high-performance ethylene (C2H4) gas sensors has garnered significant interest for achieving reliable C2H4 monitoring. In this article, Mn3O4 nanorods and Pt-modified Mn3O4 nanorods were prepared using hydrothermal and reduction methods. The samples were characterized using X-ray diffractometer (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscope (TEM), and XPS techniques. The ethylene gas-sensing performance of Pt/Mn3O4 and pure Mn3O4 was compared, and the material exhibited excellent ethylene gas-sensing performance when the Pt loading was 3 atom %. After loading Pt, the optimal operating temperature of Mn3O4 decreased from 360 to 180 °C. The synthesized 3 atom % Pt/Mn3O4 nanocomposite not only exhibited a maximum response value of 7.4-1000 ppm of C2H4 at 180 °C but also demonstrated excellent selectivity and good repeatability. The improvement in C2H4 gas-sensing performance by Pt nanoparticles is primarily attributed to the synergistic effects of spillover and the nanoSchottky barrier. Current reports of vinyl sensors, with their high operating temperatures and low response values, still fail to meet real-time monitoring requirements, and this work enables the realization of a material that exhibits higher response values at low temperatures, providing a promising material for industrial process monitoring.