Ethyl but-3-enoate is primarily used as a flavoring agent due to its fruity, pineapple-like aroma. It is commonly added to food products and beverages to enhance flavor profiles. Additionally, it serves as a versatile intermediate in organic synthesis, particularly in the production of pharmaceuticals, fragrances, and other fine chemicals. The presence of both an ester group and a terminal alkene allows for various reactions, such as polymerization, hydroformylation, or allylic functionalizations, enabling the synthesis of more complex molecules. It is also employed in the formulation of perfumes and cosmetic products for its pleasant scent.