Abstract: Advanced water electrolysis powered by renewable energy is the most ideal and environmentally friendly approach for hydrogen production, serving as a technological foundation for large-scale hydrogen energy applications. This process can significantly reduce environmental pollution from energy consumption and support China’s carbon neutrality goals. However, the high energy demands and costs of noble metals pose challenges to scaling up hydrogen production from water electrolysis. To enhance efficiency, developing low-cost yet highly efficient noble metal-free electrocatalysts for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is crucial. Understanding the mechanisms behind HER and OER helps identify factors affecting electrocatalyst efficiency and design strategies to improve performance. Moreover, replacing the energy-intensive OER with more energy-efficient reactions offers another promising way to promote hydrogen production. This review summarizes recent advancements in nonprecious transition metal-based electrocatalysts for water electrolysis. Compared to noble metal-based electrocatalysts, nonprecious transition metal-based electrocatalysts like Fe, Co, and Ni-based oxides, (oxy) hydroxides, chalcogenides, and their derivates offer abundant reserves, lower costs, and adjustable catalytic properties, making them viable alternatives for large-scale water splitting. Understanding how these materials catalyze HER and the OER in different electrolytes is key to designing strategies, such as element doping, hetero-structuring, lattice defect construction, carbon composite coupling, and surface reconstruction, to reduce energy costs of electrochemical water splitting. The mechanisms behind these strategies for enhancing water electrolysis are explained through the thermodynamics of absorbed intermediates and the reaction kinetics. Beyond reducing overpotentials, another strategy involves replacing OER with the anodic oxidation reaction of organic molecules, effectively lowering the overall voltage. This review highlights recent progress and strategies for designing efficient electrocatalysts for the anodic oxidation of diverse organics, including urea, amine, hydrazine, alcohol, aldehyde, and sulfates, in substitution of water molecules. This review also addresses the gap between lab-scale research and industry-scale application of hydrogen production. It considers research on water splitting mechanisms, catalyst development, and OER-substituting electrooxidation reactions alongside electrolyzer design, synthesis costs, working conditions, and evaluation criteria. It also compares recent advancements in state-of-the-art water electrolysis technologies and summarizes their application prospects in hydrogen production. The review aims to provide theoretical guidance for designing and synthesizing advanced transition-metal-based electrocatalysts for HER, OER, and substitution anodic reactions for energy-efficient hydrogen production while also shedding light on opportunities for energy-efficient hybrid water-splitting applications.