Plasmonic nanoparticles are a powerful way to improve the performance of modern solar cells by changing how light works at the nanoscale. The LSPRs enabled these nanoparticles to trap light more efficiently, amplify near-field interactions, and produce energetic hot carriers that may be used for photocurrent enhancement. This review provides a comprehensive overview of the underlying physical mechanisms, the material choices, the geometries of nanoparticles, the approaches for device integration, and the modelling techniques concerning plasmonic-enhanced photovoltaic systems. More emphasis will be given to advances both in theoretical understanding and in experimental demonstrations across silicon, organic, perovskite, and dye-sensitized solar cells. Additionally, the review explains how scientists are employing simulations and computational tools to enhance nanoparticle placement, reduce parasitic losses, and forecast optical–electrical behavior. Despite the progress made, challenges remain. These include material stability, thermal effects, recombination losses, and scaling up fabrication. The survey wraps up by discussing future research directions and new opportunities in plasmonic photovoltaics, especially focusing on next-generation materials, hybrid photonic–plasmonic structures, and better hot-carrier extraction methods.