<p>Lignocellulose biomass, composed of cellulose, hemicellulose, and lignin, is a vast reserve of renewable materials that are sustainable, biodegradable, and environment-friendly. Nanocellulose and nanolignin, which can be extracted from lignocellulose biomass, have recently been the research focus due to their remarkable features and properties. The synthesis and application of lignocellulosic nanolignin, cellulose nanocrystals, nanofibrils, and bacterial nanocellulose is a broad work area. The multiple steps to synthesize nanocellulose are based on the physical/mechanical, chemical, and biological treatment of lignin in the nanometer range. Nanolignin is depolymerized and fractionated into principal elements, generating lignin nanoparticles with specific functionalities. Additionally, nanocellulose and nanolignin can be functionally modified to adapt and improve their characteristics and compatibility in various applications. Utilizing lignocellulosic nanocellulose is one of the most multifaceted applications in different sectors, like packaging, biomedical, electronics, and environmental remediation. Its high aspect ratio, biological compatibility, and structural strength make it a perfect choice for developing composite materials and as a replacement for synthetic polymers from a sustainable perspective. Nanolignin is also used in various fields, such as adhesives, biocomposites, and carbon materials, for its antioxidant and UV protection properties and for enhancing mechanical properties. Overall, lignocellulosic nanocellulose and nanolignin hold great potential for designing eco-friendly materials and could be applied in many fields, significantly assisting in the transition toward a biofuel-based economy.</p>