Due to their abundance, renewability biocompatibility, biodegradability and eco-friendly aloe vera gel biopolymer reinforced with high strength and stiffness, low weight and biodegradability, cellulose nanocrystal materials to improve thermal stability of biopolymer nanocomposite. Aloe vera gel was prepared by alcohol precipitation method. Cellulose nanocrystals were prepared by sulfuric acid hydrolysis of purified mango seed shell cellulose and were used as reinforcement with aloe vera gel by solution method under strong stirring and addition of glycerol as cross- linking agents. Mango seed shell cellulose nanocrystal and the nanocomposite were characterized with ultraviolet visible, fourier transform infrared spectrophotometer, thermogravimetric analysis, differential thermogravimetric analysis, scanning electron microscopy and antimicrobial properties of the nanocomposite were also measured. A significant enhancement of the thermal stability was achieved with a small loading of cellulose nanocrystals to the aloe vera gel matrix. The results of thermal properties show that 3 wt.% CNCs containing nanocomposites have higher thermal stability followed 10 wt.% CNCs. The improvements in thermal properties suggest a close interaction between filler and matrix as shown from FTIR results increasing CNCs decreases the intensity of the peaks. The SEM image shows that good improvement in morphology and good dispersion cellulose nanocrystal in aloe vera gel matrixes. All synthesized biopolymer nanocomposites does not show any inhibition zone against, Staphylococcus aurous (+Ve), Streptococci pyrogens (+Ve) and Escherichia coli (-Ve), Kleibsiella pneumonia (-Ve).