Nickel-phosphorus/black phosphorus (Ni-P/BP) coatings were deposited on ordinary carbon structural steel (Q235 steel) by electroless plating. The tribological behavior of the Ni-P/BP coatings and traditional nickel-phosphorus (Ni-P) coating was studied comparatively on a reciprocating tribometer. The Ni-P/BP coatings exhibited good tribological performances in the water environment. Compared with traditional Ni-P coating, the friction coefficient of Ni-P/BP20 coating in deionized water and Ni-P/BP30 coating in 3.5 wt% sodium chloride decreased by 31% and 30% at 4 N, respectively. The major wear mechanism of Ni-P/BP coatings was ascribed to slight abrasive wear. This was mainly due to the combination of the higher hardness of coatings, the interlayer slip of adsorbed black phosphorus nanosheets, and the development of oxide tribofilm at the sliding interfaces.