The goal of this research is to produce renewable and biodegradable polymers based nanocomposite films. In this study, mixture of cellulose nanocrystals and cellulose nanofibers, collectively termed as nanocellulose was extracted from agricultural waste (rice straws). Nanocellulose (NC) filled sodium carboxymethyl cellulose (CMC) films were prepared via spin coating method. Various amount of NC (0, 20, 40 wt%) were added to CMC to prepare NC filled CMC nanocomposite film. Structural, chemical, morphological and thermal properties were studied through XRD, FTIR, SEM and TGA. It was found that CMC filled NC films have higher crysatllinality along UV blocking effect with 73 % visible light transmittance. Strong H-bonding between OH-group of NC and –COOH group of CMC resulted into stable and flexible nanocomposite film. Furthermore, thermal studies confirmed that strong hydrogen bonding within CMC and NC for 40 % NC filled CMC. It resulted for phase transition of nanocomposite film through fusion at higher temperature and high mass residue as compared to bare CMC and NC.