Functional biopolymers are presented as a sustainable alternative to traditional polymers, with applications in contaminant remediation, water treatment, and construction. Materials such as modified chitosan show great capacity for heavy metal adsorption and allow for reuse. In water treatment, copolymers based on chitosan or starch achieve turbidity reductions of up to 99% with lower doses than conventional coagulants. Likewise, nanocellulose membranes stand out for their high permeability and efficiency in removing pharmaceutical contaminants. In construction, the incorporation of chitosan in mortars or cements improves certain mechanical properties, although with a slight increase in life cycle emissions. However, technological challenges include high production costs, limited scalability, and a lack of clear regulation. In the biomedical field, drug delivery systems (DDS) and smart gels still face limitations in terms of resistance and regulations. The positive environmental impacts of biopolymers include biodegradability, reduced carbon footprint, and contributions to the circular economy. Future research is focused on more resistant biopolymers, bioinks for 3D printing, textile coatings, and applications in regenerative medicine. Functional biopolymers represent a transformative technology, although challenges remain in terms of cost, regulation, and scalability.