Ni–P alloy coatings with a phosphorus content of 4.44 wt% were prepared by the direct current electrodeposition technique. After being annealed at 400 °C, all the Ni–P coatings mainly exhibited a nanocrystalline structure comprising nanocrystalline Ni and Ni₃P precipitates. The Ni–P coatings were further subjected to quenching treatment at various temperatures. The effects of the quenching process on the microstructural evolution and tribological properties of the Ni–P coatings were investigated. A further quenching process at 400 °C caused a decrease in grain size as well as increases in hardness and wear resistance, which was attributed to the re-strengthening effect of the combination of the grain refinement effect and the dispersion of Ni₃P. The wear resistance of the quenched Ni–P coatings increased with a decrease in grain size in accordance with the inverse Hall–Petch relationship.