Gear transmission is a prevalent method in mechanical transmission; however, its effectiveness is often compromised by excessive wear on the meshing surfaces, primarily attributed to inadequate lubrication. This wear substantially hampers the overall service life of gears. In this study, a chemically deposited FeS coating, boasting favorable lubricating characteristics, was applied to 20CrMnTi gear steel to enhance the tribological performance of gear surfaces. The wear morphology and composition of the FeS coatings were analyzed using SEM, EDS, XRD, white light interferometry, and Raman spectroscopy. The tribological properties of the FeS coatings under dry friction conditions were examined. The FeS coating, with a thickness of about 5.4 μm, exhibited commendable purity, featuring an abundance of aggregated micron-sized sheets on its surface. Results revealed that the FeS-coated samples demonstrated reduced wear levels and friction coefficients compared with the gear steel substrate. Furthermore, the friction coefficient and wear volume of the FeS coating exhibited a noticeable decrease with increasing applied load. Although the friction coefficient of the FeS coating remained relatively stable with increasing rotational speed, wear volume increased. Microscopic analysis revealed that higher loads facilitated the spreading of the lubricating film, whereas elevated rotational speeds intensified oxidative and adhesive wear of the material. Throughout the experiment, the lubricating film transferred to the counterpart surface, forming a transfer film that impeded direct contact between the microasperities of the frictional pair. Even after the coating layer was fully worn, the transfer film can still maintain the long-lasting lubricating performance between the friction pairs and reduce the material wear.