Regulating the Electronic Structure via Multi‐Transition Metals in Nanoporous High‐Entropy Perovskites for Boosted Alkaline Hydrogen Evolution

High‐entropy perovskite oxides (HEPOs) exhibit great application prospects in electrocatalysis due to their enormous compositional design space. Herein, nanoporous La‐based HEPOs were synthesized for the first time through a dealloying and annealing strategy, and employed as electrocatalysts for alkaline hydrogen evolution reaction (HER). The HEPOs exhibit single‐phase cubic perovskite structures and three‐dimensional nanoporous architecture. Among them, L5M‐0Cr (La(Ni 0.2 Mn 0.2 Fe 0.2 Co 0.2 Ru 0.2 )O 3‐δ ) demonstrates exceptional alkaline HER activity, achieving a low overpotential of ∼50.6 mV at ‐10 mA cm − 2 and a small Tafel slope of ∼60.1 mV dec − 1 , surpassing most reported perovskite‐based catalysts and exceeding Pt/C at high current densities. Additionally, L5M‐0Cr shows remarkable stability over 120 h of continuous operation and delivers promising performance in overall water‐splitting systems. Structural characterizations, in situ Raman spectroscopy, and density functional theory (DFT) calculations reveal that lattice distortion and charge redistribution within high‐entropy systems can effectively modulate electronic structure, inducing strong hybridization between Ru 4d and O 2p orbitals. Theoretical simulations are employed to establish the volcano‐type correlation between hydrogen adsorption free energy (ΔG *H ) and HER exchange current density (log i 0 ). This work demonstrates that high‐entropy design synergistically optimizes the structural, electronic, and catalytic properties of perovskites, providing a promising strategy for developing efficient electrocatalysts in energy conversion applications.