The intrinsically sluggish kinetics of the oxygen evolution reaction (OER) remains a critical bottleneck for efficiently electrochemical water splitting, demanding catalysts that are both highly active and robust. Herein, this work overcomes this challenge through a heterostructure engineering strategy, fabricating a strongly coupled Ce(OH)3/NiFe2O4 heterogeneous interface on nickel foam (NF). This unique configuration is shown to critically modulate the catalyst’s electronic structure and electrochemical reconstruction, unlocking substantial gains in OER performance. The optimized Ce(OH)3/NiFe2O4/NF catalyst exhibits exceptional OER performance, requiring a low overpotential of only 192 mV to achieve a current density of 10 mA‧cm−2 and a small Tafel slope of 40.7 mV‧dec−1, and demonstrating outstanding long-term stability for 400 h at 400 mA‧cm−2 in 1 M KOH. Mechanistic studies, including pH-dependent kinetics and molecular probe experiments, reveal that the OER process predominantly follows the lattice oxygen-mediated mechanism (LOM) of Ce(OH)3/NiFe2O4/NF, bypassing the scaling relations limitations of the conventional adsorbate evolution mechanism (AEM). Moreover, the in-situ Raman spectroscopy studies reveal a substantially decreased formation potential of the active NiOOH phase, while density functional theory (DFT) computations demonstrate that the interfacial coupling optimizes electronic structure via weakened metal-oxygen bonds and a modulated O-p band center in Ce(OH)3/NiFe2O4/NF. Besides, the integrated Pt/C||Ce(OH)3/NiFe2O4/NF electrolyzer exhibits excellent overall water splitting activity, demanding exceptionally low cell voltages of only 1.44 V and 1.58 V to achieve 10 and 100 mA‧cm−2, respectively. This work highlights the efficacy of rare-earth-based interface engineering in activating the LOM pathway and provides a valuable strategy for designing high-performance OER electrocatalysts.