Diamine Green B is primarily used as a dye in the textile industry for coloring fabrics, especially wool and silk, due to its ability to produce vibrant green shades. It is also employed in the paper industry for tinting paper products, providing a consistent and durable color. Additionally, it finds application in biological staining, where it helps in highlighting specific structures under microscopic examination. Its stability and colorfastness make it suitable for use in various industrial dyeing processes.