It is of great significance to develop efficient and robust oxygen evolution reaction (OER) electrocatalysts based on inexpensive and earth-abundant materials to enable water splitting as a future renewable energy source. Herein, the in situ grown CoMn-MOF-74 on nickel foam and their use as active electrodes for high-performance water-oxidation catalysis are reported. In alkaline media, the binder-free three-dimensional (3D) electrode shows superior OER activity with a current density of 10 mA cm−2 at a small overpotential of 260 mV, a Tafel slope of 58.2 mV dec−1, as well as excellent stability, making it one of the most active OER catalyst. Such high performance is attributed to increased electrochemically active areas, accelerated electron transport capability and the synergy between metal–organic framework (MOFs) and Ni substrate. This work elucidates a promising electrode for electrochemical water oxidation and enriches the direct application of MOF materials for future clean energy conversion and storage systems.