The effect of Nypa fruticans (NF) content and acrylic acid on tensile properties, X-ray diffraction, thermogravimetric analysis, and morphology of NF regenerated cellulose (RC) biocomposite films was studied. NF RC biocomposite films were produced by dissolving NF and microcrystalline cellulose in the mixture of N,N-dimethylacetamide (DMAc)/lithium chloride. The result found that the addition of NF increased the tensile strength and Young's modulus, but reduced the elongation at break of the NF RC biocomposite films. The crystallinity index, thermal stability, moisture content, and weight loss of enzymatic biodegradation of the NF RC biocomposite films also improved as the NF content increases. The presence of NF modified with acrylic acid exhibits higher tensile strength, Young's modulus, and elongation at break compared to unmodified NF RC biocomposite films. The crystallinity index, thermal stability, moisture resistivity, and stability towards enzymatic biodegradation of the NF RC biocomposite films increased after modification with AA. The improvement of filler-matrix adhesion was verified by SEM study.