<p>The global transition toward a carbon–neutral energy economy demands durable and scalable technologies for green hydrogen production by water electrolysis. Water electrolysis has emerged as the most promising method, yet the deployment of proton exchange membrane (PEM), alkaline, and anion exchange membrane (AEM) electrolyzers at industrial current densities is severely challenged by, intermediate formation, catalyst degradation and loss of durability. Conventional ex-situ characterization methods are useful for static information but fail to capture the dynamic restructuring of catalysts under realistic industry-scale operating conditions. In-situ/operando Raman spectroscopy has therefore become a vital diagnostic tool, offering molecular-level insights into structural transformations, oxidation state evolution, and intermediate formation directly at the catalyst–electrolyte interface. Operando Raman spectroscopy has recently advanced to monitor Raman spectroscopy during electrocatalysis for structural transitions within the catalyst layer, interfacial species formation at the electrode/electrolyte interface, and local electrolyte environment near the electrode in industrially applicable electrolyzers. These developments are briefly reviewed in this review. Examples of cases where Raman methods have been used to identify transitory species, dissolution processes, and surface reconstructions under high current densities are highlighted. Operando methods’ benefits, drawbacks, and prospects are examined in order to present a comprehensive picture of catalyst stability and durability. By bridging fundamental insights with industrial operating conditions, operando Raman spectroscopy is positioned as a powerful platform to accelerate the rational design of stable, high-performance electrocatalysts for large-scale green hydrogen production.</p>