Numerous atomically precise coinage metal nanoclusters have been synthesized, exhibiting diverse structures and promising properties for catalytic and other functional applications. However, silver nanoclusters featuring layered core structures remain largely unexplored, limiting investigations into the effects of atomic arrangements on catalytic functions. Herein, we report the synthesis and atomic level structure of a novel thiolate-phosphine co-stabilized silver nanocluster, Ag₂₆(SR)₁₆(DPPE)₄Cl₂ (denoted as Ag₂₆), where SR is 3,5-bis(trifluoromethyl)benzenethiolate and DPPE is 1,2-bis(diphenylphosphino)ethane. Single-crystal X-ray diffraction analysis reveals that Ag₂₆ comprises a three-layered Ag₁₈ core, with each layer consisting of six silver atoms arranged in a distorted parallelogram configuration. This Ag₁₈ core is stabilized by four Ag₂(SR)₄(DPPE) metal-ligand motifs and two chlorides. Notably, TiO₂-supported Ag₂₆ nanoclusters (Ag₂₆/TiO₂) demonstrated promising photocatalytic performance for solar-driven hydrogen production, achieving a hydrogen evolution rate of 2006 μmol·g⁻¹·h⁻¹, representing 16.2- and 6.5-fold enhancements compared to bare TiO₂ support and similarly sized Ag₂₅/TiO₂ nanoclusters, respectively. The layered atomic arrangement in the Ag₂₆ core favorably regulates the energy level alignment with TiO₂, leading to efficient photogenerated charge separation and enhanced catalytic activity. This work highlights the potential of structurally tailored silver nanoclusters and offers valuable insights for the design of advanced materials for energy conversion applications.