Enhancing photoluminescence (PL) of semiconducting 2D materials is proven essential for many applications related to optoelectronics and sensing. Here, we demonstrate synergistic PL enhancement in 2D materials by incorporating silver plasmonic nanodiscs in defect-induced monolayer molybdenum disulfide (MoS2) for luminescent quench sensing of dopamine with high accuracy and selectivity. We develop a hole-array perforated 2D MoS2 embedded with plasmonic silver dimers to harmonize the surface plasmon resonance with the PL wavelength of monolayer MoS2, which enhance it by 56-fold. We implemented the optimized perforated MoS2/dimers platform as a catalytic assay for on-chip PL quenching detection of dopamine, achieving a low limit of detection of 9.3 nM. This approach opens avenues of high-performance molecular sensing applications by improving the PL emission of 2D materials.