In this study, the surface of aluminum powder was uniformly coated with in situ reduced graphene oxide (r-GO) sheets (Al/r-GO). The Ni powder, Al2O3powder, and Al/r-GO powders were mixed uniformly in a mass ratio of 20:6:4. In situ rGO-reinforced Ni–Al intermetallic composite coatings were successfully prepared using low-pressure cold spraying and subsequent heat treatment. The microstructure and phase of the composite coatings were characterized using X-ray diffraction (XRD), Raman spectroscopy, and scanning electron microscopy (SEM). The high-temperature wear test was conducted at 200 °C, 400 °C, and 600 °C to understand the mechanism. The results indicate that the in situ rGO-reinforced Ni–Al intermetallic composite coatings exhibit a 33.3% lower friction coefficient and 26% lower wear rate in comparison to pure Ni–Al intermetallic coatings, which could be attributed to the generation of an easy-shearing transferred film between the coating and grinding ball.