Green　hydrogen　holds　immense　promise　in　combating　climate　change　and　building　a　sustainable　future.　Owing　to　its　high　power-to-gas　conversion　efficiency,　compact　structure,　and　fast　response,　the　proton　exchange　membrane　water　electrolyzer　(PEMWE)　stands　out　as　the　most　viable　option　for　the　widespread　production　of　green　hydrogen.　However,　the　harsh　operating　conditions　of　PEMWE　make　it　heavily　dependent　on　noble　metal-based　catalysts　(NMCs)　and　incur　high　operational　and　maintenance　costs,　which　hinder　its　extensive　adoption.　Hence,　it　is　imperative　to　improve　the　performance　and　lifespan　of　NMCs　and　develop　advanced　components　to　reduce　the　overall　costs　of　integrating　PEMWE　technology　into　practical　applications.　In　light　of　this,　the　fundamental　design　principles　of　NMCs　employed　in　acidic　water　electrolysis　are　summarized,　as　well　as　recent　advancements　in　compositional　and　structural　engineering　to　enhance　intrinsic　activity　and　active　site　density.　Moreover,　recent　innovations　in　stack　components　of　practical　PEMWE　and　their　impact　on　cost-benefit　and　lifespan　are　presented.　Finally,　the　current　challenges　are　examined,　and　potential　solutions　for　optimizing　NMCs　and　PEMWE　in　electrocatalytic　hydrogen　production　are　discussed.　©　2024　Wiley-VCH　GmbH.