Two types of hybrid nanostructures were fabricated for surface plasmon-enhanced yellow light emission. One is Ag triangular nanoplates (TNPs) and Rhodamine B (RhB) co-doped poly(methyl methacrylate) (PMMA) structure and the other one is Ag TNPs attached on the surface of RhB-doped PMMA structure. The light emission dependence was investigated as a function of concentration and size of the Ag TNPs. Compared to that of without Ag TNPs, a 13.8-fold enhancement on yellow light emission was obtained by attaching 0.015-nM Ag TNPs on the RhB-doped PMMA layer, while a maximum of 24-fold emission enhancement was obtained by doping 0.015-nM Ag TNPs into the RhB-doped PMMA layer. The hybrid nanostructures would be potentially used as a component of light-emitting devices or solar energy conversion units.