Ni-P-SiC_P coatings were deposited on 42CrMo steel by electroless plating. The surface morphologies and phase structures of the Ni-P-SiC_P coatings processed under different SiC_P concentrations at different heat treatment temperatures were analyzed. The microhardness, corrosion resistance, and wear resistance of the Ni-P-SiC_P coatings were studied. Results show that Ni-P-SiC_P coatings exhibit cauliflower-like morphology. Increasing the SiC_P concentration can reduce the size of cellular structure. The microhardness and corrosion resistance are initially increased and then decreased with the increase in SiC_P concentration. The maximum microhardness and corrosion potential are 7379 MPa and -0.363 V, respectively, when the SiC_P concentration is 5 g/L. The Ni-P-SiC_P coatings exhibit an amorphous structure, and the width of the diffuse diffraction peak becomes narrower with the increase in SiC_P concentration. It is suggested that SiC_P inhibits the deposition of P and promotes the microcrystalline transformation. After heat treatment at 350 °C, the Ni-P-SiC_P coatings are crystallized, resulting in the precipitation of Ni₃P phase. Heat treatment at 400 °C for 1 h maximizes the structure. The synergistic effect of the Ni₃P precipitate phase and SiC_P dispersion phase promotes the densification of the cellular structure, leading to the optimal microhardness (13 828 MPa), optimal corrosion resistance (-0.277 V), and excellent wear resistance. The wear mechanism is dominated by micro-cutting abrasive wear with slight adhesive and oxidative wear.