Cellulose and chitin are abundant, natural, renewable and biodegradable polymers which could be broken down into nano sized crystalline entities, using a top-down approach. In most cases, an aqueous suspension of these nano crystallites are prepared by acid hydrolysis process and has high specific mechanical properties making them potential reinforcements in various polymer matrices. In this work, we present the processing and characterization of nanoreinforcements from waste materials such as cellulose and chitin and their polymer nanocomposites using natural rubber matrix (NR) or synthetic rubber matrix, carboxylated styrene butadiene rubber (XSBR). The isolated chitin whiskers had a length ranging from 100 to 500 nm and diameter ranging from 10 to 80 nm and cellulose nanowhiskers had diameters between 4-14 nm. The addition of 4.32 wt of % chitin nanowhiskers resulted in an improvement of 1400 % for tensile strength. The cellulose nanowhiskers gave good mechanical and tensile improvements on NR matrixes and Atomic force microscopy (AFM) was carried out to examine the size and structure of chitin and cellulose nanowhiskers and scanning electron microscopy (SEM) used for the morphological study of both type of nanocomposites. It may be concluded that the biobased nanostructures have great potential in reinforcing natural and synthetic elastomers and the reinforcing potential depends on the dispersion and distribution of the nanocrystals in the matrix as well as the interaction between the phases.