Reactive Blue 19 is widely used in the textile industry for dyeing cellulosic fibers such as cotton, rayon, and linen. It forms strong covalent bonds with the fiber under alkaline conditions, resulting in excellent color fastness to washing and light exposure. This dye is particularly valued in batch and continuous dyeing processes where bright blue shades are required.

It is also applied in the printing of textiles, offering good reproducibility and sharp pattern definition. Due to its reactivity, it requires careful control of pH and temperature to maximize fixation and minimize hydrolysis.

In addition to textiles, Reactive Blue 19 is used in paper dyeing to produce vibrant blue paper products. It has found use in some laboratory applications as a model dye in studies of wastewater treatment, especially in research focused on decolorization and degradation of effluents from textile industries.

Environmental concerns exist due to its potential to form harmful byproducts during degradation, so its use is often accompanied by efforts to improve dye uptake efficiency and reduce discharge into water systems.