Nowadays we are extremely dependent on various synthetic plastic materials to maintain the massive demand, therefore, both the industries and mankind have been generating a massive amount of plastic waste which is so hazardous for the total environment due to their nonbiodegradable nature. To solve this problem by replacing the fossil-based plastic materials with ecofriendly biopolymers in this current study we will be described a novel method for producing Crystalline Nano Cellulose (CNC) from the waste sugarcane leaf sheaths (SLSF) fibers as a green reinforcing agent. The waste-to-wealth approach aims to elevate agricultural residues, particularly SLSF, by transforming them into high-quality CNCs for use in a variety of sectors. SLSF was initially washed with detergent to remove impurities, followed by alkali treatment and bleaching operation before CNC manufacture using acid hydrolysis (60% H2SO4). The resulting materials were characterized using Fourier transform infrared (FTIR) spectroscopy, Scanning electron microscopy (SEM), X-ray diffraction (XRD), Thermogravimetric analysis (TGA), Differential thermogravimetry (DTG), and Differential thermal analysis (DTA). FTIR indicates the newly produced CNCs is very much rich with active sites like –OH, -NH, -COOH, -C-O-C-, etc., while SEM revealed the raw fiber surface was rough, whereas the surface of CNCs became smooth even after the removal of lignin, fatty, and waxy compounds. Overall, acid hydrolysis was shown to increase the crystallinity of bleached SLSF while reducing cellulose dimensions to the nanoscale. After analysis it was revealed that most CNC particle size was around 100 nm. The outstanding properties of CNCs, including as high strength, biodegradability, and low environmental impact, make them ideal candidates for reinforcing composites, improving medicine delivery systems, and aiding new electronics. Ongoing research and technology advancements in integrating CNCs into many applications have the potential to alter industries looking for sustainable and high-performance materials.