Tetrapotassium decatungstate is primarily used as a photocatalyst in organic synthesis. It enables light-driven reactions under mild conditions, especially in oxidation processes and C–H bond activation. The compound is effective in promoting electron transfer reactions when exposed to UV or visible light, making it valuable in green chemistry applications where reducing environmental impact is important.

It is also employed in environmental chemistry for the photodegradation of pollutants, helping break down organic contaminants in water under irradiation. Due to its stability and reusability, it is suitable for repeated catalytic cycles in industrial and laboratory settings.

Additionally, tetrapotassium decatungstate finds use in polymer chemistry as a photoinitiator, supporting the cross-linking or curing of resins and coatings when exposed to light. Its role in photoresponsive materials continues to be explored in advanced material science and chemical sensing systems.