Transition metal phosphides have recently emerged as promising alternatives for oxygen evolution reaction (OER). Herein, the OER performance of CoP nanowires was significantly enhanced by coupling with the cobalt-iron layered double hydroxide (CoFe-LDH) nanosheets. The three-dimensional (3D) CoP@CoFe-LDH nanoarays heterostructure was fabricated by the sequential steps of hydrothermal process, phosphorization and electrodeposition. The as-prepared CoP@CoFe-LDH possesses well core–shell structure with a synergistic heterointerface between CoP and CoFe-LDH, in which the CoP core improves the conductivity and the CoFe-LDH shell affords abundant active sites. Furthermore, the 3D hierarchical architecture facilitates the electrolyte ions access and O2 gas liberation. Consequently, the optimized CoP@CoFe-LDH exhibits excellent OER performance with low overpotential (240 mV @ 40 mA cm−2), small Tafel slope (69.2 mV dec-1), superior intrinsic activity and high stability in 1 M KOH. This study demonstrates an efficient route to design the advanced OER catalysts by constructing the 3D core–shell heterostructure.