The pulp and paper industry is a significant contributor to global wastewater pollution, discharging large volumes of effluents laden with organic matter, suspended solids, chlorinated compounds, and recalcitrant lignin derivatives. Traditional treatment methods often fall short in completely removing these persistent pollutants, leading to environmental degradation and ecological risks. In recent years, nanotechnology has emerged as a promising solution to address these challenges due to its superior surface reactivity, high adsorption capacity, and tunable physicochemical properties. This chapter explores the advancements in nanomaterials, such as metal and metal oxide nanoparticles, carbon-based nanostructures, and nano-enabled membranes for the treatment of pulp and paper mill effluents. The mechanisms of contaminant removal, including adsorption, photocatalysis, and membrane filtration, are critically analyzed. Furthermore, the chapter discusses the environmental implications, scalability, and prospects of integrating nanotechnology into industrial wastewater management systems. Emphasis is placed on the development of sustainable, cost-effective, and efficient nanotechnological approaches to support the transition toward cleaner production and the circular economy in the pulp and paper sector.