Developing well-defined nanostructures with superior surface-enhanced Raman scattering (SERS) performance is a critical and highly desirable goal for the practical applications of SERS in sensing and analysis. Here, a SERS-active substrate was fabricated by decorating a MoS₂ monolayer with Ag nanowire (NW) and nanoparticle (NP) structures, using a spin-coating method. Both experimental and theoretical results indicate that strong SERS signals of rhodamine 6G (R6G) molecules can be achieved at "hotspots" formed in the Ag NW-Ag NP-MoS₂ hybrid structure, with an enhancement factor of 10⁶. The SERS enhancement is found to be strongly polarization dependent. The fabricated SERS substrate also exhibits ultrasensitive detection capabilities with a detection limit of 10^–11 M, as well as reliable reproducibility and good stability.