This work presents a strategy to obtain plasmonic plastics by conventional large scale polymer processing methods using metal nanoparticles (Au and Ag) supported on sepiolite fibers acting as carriers. Two conventional polymers, polyethylene and polystyrene, have been used as matrices, and composites were prepared up to high inorganic contents. The resulting composites exhibited at all loadings the corresponding optical absorption plasmon bands ascribed to the metal nanoparticles. In addition the sepiolite fibers acting as carriers remarkably improved the thermal stability and produced mechanical reinforcement of the polymer matrices as well as they appear invisible due to the index matching with the matrix. Therefore, highly transparent and robust plasmonic plastics can be easily prepared by industrially scalable processing techniques.