In this study, the effect of plasmonic core-shell structures, consisting of dielectric cores and metallic nanoshells, on energy conversion in dye-sensitized solar cells (DSSCs) is investigated. The structure of the core-shell particles is controlled to couple with visible light so that the visible component of the solar spectrum is amplified near the core-shell particles. In core-shell particle – TiO2 nanoparticle films, the local field intensity and light pathways are increased due to the surface plasmons and light scattering. This, in turn, enlarges the optical cross-section of dye sensitizers coated onto the mixed films. When 22 vol% of core-shell particles are added to a 5 μm thick TiO2 film, the energy conversion efficiency of DSSCs increases from 2.7% to 4.0%, in spite of a more than 20% decrease in the amount of dyes adsorbed on the composite films. The correlation between core-shell particle content and energy conversion efficiency in DSSCs is explained by the balance among near-field effects, light scattering efficiency, and surface area in the composite films.