Ethyl isobutyl phthalate is primarily used as a plasticizer in the production of flexible polyvinyl chloride (PVC) products. It enhances the flexibility, durability, and workability of materials such as vinyl flooring, cables, and synthetic leather. Additionally, it is employed in coatings and adhesives to improve their performance and longevity. Its compatibility with various polymers makes it a valuable component in the manufacturing of consumer goods and industrial materials.