This review highlights the latest research studies about the use of lignocellulosic nanocellulose-based composites in the applications of wastewater treatment and waste-oil remediation. Three types of composites are described, including nanocellulose-based aerogels, nanocellulose-based membranes, and new wood-based morph-genetic materials. The fabrication and modification techniques to prepare these composites are introduced. The effectiveness and efficiency of these composites in the adsorption of heavy metal ions, dyes, and micropollutants, separation of oil and water, and catalytic degradation of organic pollutants are discussed, respectively. In addition, the challenges and opportunities of nanocellulose-based composites in these areas and the future research directions of lignocellulosic nanocellulose composites for wastewater treatment and waste-oil remediation are addressed.