The nanocellulose and its nanocomposites have significant importance in the most economic sectors of applications. This research involves the synthesis of nanocellulose from Albizia lebbeck wood sawdust. Quantitative evaluations of chemical components present in the sawdust of a native hardwood species Albizia lebbeck were determined by chemical analysis method. The results revealed that the approximate amount of hot water extractives, 96% ethanol extractives, alpha-cellulose, hollocellulose, hemicellulose, lignin and ash content were 6.9%, 7.31%, 40.72%, 65.10%, 24.38%, 25.67%, and 1.10% respectively. Nanocellulose was synthesized from the extracted alpha-cellulose by acid hydrolysis method. Fourier-transform infrared spectroscopy (FTIR) characterizations have been done for Albizia lebbeck sawdust, extracted alpha-cellulose and synthesized nanocellulose respectively. The average diameter of synthesized nanocellulose was found 155.6 nm by particle size analyzer. Nanocellulose with different weight percentages (2%, 4%, 6%, 8% and 10%) were reinforced with poly(vinyl chloride) (PVC) to prepare nanocomposites by solution casting method. The thermal stability of pure PVC, nanocellulose and 2wt% nanocellulose–PVC nanocomposite was investigated and the result revealed that 2 wt% nanocellulose reinforced PVC nanocomposites is thermally more stable than the nanocellulose and pure PVC. The tensile properties of all nanocomposites were counducted by universal testing machine (UTM) and the highest tensile strength was obtained for 2 wt% nanocellulose reinforced PVC nanocomposites. The scanning electron microscope (SEM) images of 2 wt% nanocellulose reinforced PVC nanocomposites also exhibited the uniformly dispersion of nanocelulose in nanocomposite.