Wastewater is an undesirable by-product of human activity that constitutes an enormous global problem. Considering domestic and industrial wastes, an ongoing excess in their production is observed, counted in billions of hectolitres. Moreover, the growing needs of the human population indicate that the amount of wastewater will constantly increase annually. The next aspect is economic growth in numerous countries that inflicts wastewater production, especially that coming from industry. The rising amount of wastewater creates new environmental threats that should be mitigated to maintain CO2 emissions at an acceptable level. In the era of increasing ecological awareness, sustainable solutions are sought for effective wastewater management. One of the leading directions is the use of biomaterials for this purpose, both those specially functionalised for a given application, as well as those derived from waste biomass of industrial processing (e.g. lignocellulose, bran, chitin, collagen, gelatine, fruit pomace, brewer's grain, etc.). The most challenging is the development of new bio-based materials for wastewater treatment, especially for developing countries that require easy-to-use and cost-effective solutions to mitigate the challenges of developing economies and their impact on the environment. In this chapter, authors aim to overview different types of wastewater with specific properties and the possibilities of their effective processing using various pro-ecological solutions involving bio-based materials. First, the diversity of chemical composition of wastewater from different sectors is provided to demonstrate noticeable differences in the amount, type and concentration of the compounds they contain. Next, biomaterials with potential for use in sustainable wastewater treatment are classified and characterised. The main part of the chapter concerns the application of bio-based materials as high-performance pro-ecological tools in the monitoring, neutralisation, treatment, and valorisation of wastewater. Among others, the use of biomaterials in separation, sorption, detection, and conversion of hazardous compounds is discussed. The chapter also provides information on the latest innovative solutions and future prospects for sustainable wastewater treatment using bio-based materials.