<p>This research aims to enhance the structural and optical properties of porous silicon (PSi) for advanced sensing applications through a novel multilayer surface modification. A new modification approach was successfully applied to PSi layers by incorporating a multilayer structure composed of silver (Ag) and gold (Au) nanoparticles along with multi-walled carbon nanotubes (MWCNTs). The modification was achieved via a simple room-temperature immersion process in ionic solutions. The original porous structure was fabricated using a laser-assisted electrochemical etching technique on a high-resistivity silicon substrate (100 Ω·cm), utilizing a 635 nm diode laser with a power density of 150 mW. Comprehensive characterization revealed significant improvements after modification. Increased nanoparticle surface density due to MWCNT integration, enhanced specific surface area up to 339.6 m²/g. Reduced grain size to approximately 1.8 nm. A photoluminescence blue shift of 79 nm. An improvement factor of 9.23 compared to the unmodified PSi. The proposed multilayer modification presents a simple, effective, and low-cost strategy for improving PSi, making it a promising platform for various sensing applications. Also,the increase in surface area after adding MWCNTS from 182.16 g/ m² to 333.96 g/m2, is considered one of the most important enhancements contributed by adding MWCNTS.</p>