We report a synthetic method to enhance the electrocatalytic activity of birnessite for the oxygen evolution reaction (OER) by intercalating Ni2+ ions into the interlayer region. Electrocatalytic studies showed that nickel (7.7 atomic %)‐intercalated birnessite exhibits an overpotential (η) of 400 mV for OER at an anodic current of 10 mA cm−2. This η is significantly lower than the η values for birnessite (η≈700 mV) and the active OER catalyst β‐Ni(OH)2 (η≈550 mV). Molecular dynamics simulations suggest that a competition among the interactions between the nickel cation, water, and birnessite promote redox chemistry in the spatially confined interlayer region.