The purpose of this study was to obtain and characterize cellulose nanocrystals (CNCs) made from anchote (Coccinia Abyssinica) bagasse (AnchB). Anchote cellulose (AnchC) was isolated from AnchB by alkali treatment with NaOH followed by bleaching with NaOCl. After acid hydrolysis (with H₂SO₄) and ultrasonic disintegration of AnchC, anchote cellulose nanocrystals (AnchCNC) were produced. The chemical components of AnchB and AnchCNC were determined. AnchB, AnchC, and AnchCNC were characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), and size distribution analyzer. The chemical treatments (alkali treatment, bleaching, and acid hydrolysis) effectively removed hemicelluloses and lignin from AnchB, according to changes in the FTIR spectra. The thermal stability of AnchCNC was reduced after acid hydrolysis due to the introduction of sulfate groups. XRD measurements revealed that chemical treatments increased crystallinity by 160%. SEM exhibits that the chemical treatments effectively removed the amorphous fractions. Zetasizer analysis showed that AnchCNC had an apparent average diameter of 92 nm and zeta potential value of −21.0 mV. The tensile strength and Young’s modulus of the anchote starch/AnchCNC nanocomposite film was increased by 211% and 182%, respectively by addition of 5 wt% AnchCNC.