In the present study, berberine, a natural dye, was modified by a simple chemical conversion with the aim of improving its dyeing properties. The modified berberine was successfully applied in the dyeing and functional finishing of a variety of fabrics. The uptake of the modified berberine by acrylic fabric was more sensitive to the pH of dye bath than that of berberine. The silk, cotton, wool, polyamide, and polyester fabrics dyed with the modified berberine all showed greater exhaustion than with berberine. In addition, the textile treated with the modified berberine showed better color fastness and much better UV protection ability. This study shows that this novel modified berberine can be suitably applied to prepare multifunctional textiles for many fabrics.