Our country's environmental pollution has seriously threatened the natural world. Among all the pollution, water pollution is becoming a great concern as it accumulates unwanted toxic contaminants in water bodies. Insufficiently treated or untreated wastewater greatly contributes to releasing contaminants into the water bodies that are being used for different purposes. These pollutants are becoming bioaccumulated and causing serious threats to the aquatic ecosystem. Many wastewater treatment technologies are working to overcome this problem. Despite all the technologies, seaweed adsorption technology has an excellent impact on various industrial sectors because of its substantial significance. i.e., low cost, easy availability, large biomass, easy handling, obvious, and high efficiency with a low-cost investment compared to other artificial techniques used and also used for sewage treatment management. Hence, seaweed adsorption is an obvious technique to remove all the pollutants. However, biosorption is also an efficient method for trapping the contaminants in water bodies by using naturally available seaweed such as removing disinfection byproducts, heavy metals like copper and zinc, phenolic compounds, various inorganic dyes, and nitrites from water bodies. Seaweeds have been used as a low-cost adsorbent. The biosorption by seaweeds should be used as an alternative to other wastewater techniques. So, this book chapter highlights the importance of seaweed biosorption as a promising technique for treating contaminated water because of its eco-friendly nature.