Plasmonic nanoantennas with efficient scattering and strong electromagnetic field confinement were integrated to atomically thin transition metal dichalcogenides (TMDC) to shed light on the nanoscale light-matter interactions. Herein, we optimized the quadrupole gap surface plasmonic (QGSP) structure by Taguchi design to maximize field enhancement and integrated to CVD grown bilayer molybdenum disulfide (MoS₂), beneficially tuning the optical properties of bilayer MoS₂. The optimized QGSP structure with 27.87 factor enhanced performance and advantageous 1cm² continuous bilayer MoS₂ finds potential application for hydrogen evolution reaction (HER) with superior outcome. MoS₂@QGSP act as an excellent photocatalyst for HER activity on account of accelerated electron injection process in comparison to electron-hole pair recombination supported from skilled light trapping capacity of QGSP structure and plentiful accepting sites of large surface continuous bilayer MoS₂ film. This report demonstrates the gap surface plasmon enhanced intrinsic catalytic properties of bilayer MoS₂ for photocatalytic reactions.