Rationally designing highly active oxygen evolution reaction (OER) electrocatalysts with robust stability is critical for industrial electrochemical water splitting. Hierarchical iron–nickel oxyhydroxide nanosheets directly grown on porous TiFe₂-based intermetallics are designed and prepared as OER catalysts. The best-performing nanosheets only need 295 mV to achieve 100 mA cm⁻², along with exceptional durability at a high current density of 1000 mA cm⁻². This work introduces a scalable strategy for producing robust OER catalysts that have potential for industrial applications.