Methyl trans-9-octadecenoate is widely used in the production of biodiesel due to its properties as a fatty acid methyl ester. It serves as a key component in renewable energy solutions, offering a cleaner alternative to traditional fossil fuels. In the cosmetics industry, it is utilized as an emollient and skin-conditioning agent, helping to improve the texture and moisture retention of skincare products. Additionally, it finds application in the formulation of lubricants and plasticizers, where it enhances flexibility and reduces friction in various industrial materials. Its role in research and development includes serving as a standard or reference compound in analytical chemistry for studying lipid profiles and fatty acid compositions.