Natural polyphenols are broadly found in plant sources and considered bioactive molecules. In this chapter, a critical review of the bioactivities of natural polyphenols and their application onto textile materials is presented. The application of polyphenols onto textile materials yielded desirable functionalities such as natural color, as well as antioxidant, antimicrobial, and ultraviolet protection properties. Polyphenols can be grafted onto the fibers by enzyme-mediated and non-enzyme-mediated techniques, and their bioactivities can be varied depending on the types of phenolic compounds. Polyphenol grafting onto textile fibers is a promising alternative to conventional synthetic dyestuffs in the development of environmentally friendly coloration and functionalization of textiles.