<p>During the preparation of alcohol from grains, substantial amounts of value-added byproducts, known as distillers' grains, are generated. These byproducts are rich in nutrients, including dietary fiber (hemicellulose, cellulose, and lignin), protein, simple sugars (glucose, xylose, and arabinose), minerals, vitamins, and lipids. However, the rapid global expansion of the alcohol industry has resulted in tens of thousands of tons of distillers' grains remaining without appropriate disposal methods. Therefore, it is essential to identify innovative solutions that reintegrate waste and byproducts into the production cycle, thereby yielding high-quality products. In this review, we first summarize the classification, sources, and components of distillers' grains. We then analyze and compare their utilization value and extraction technologies, as well as their development and market status. Additionally, we summarize the categories of active substances found in distillers' grains and assess the current status and potential applications for resource recycling. Ultimately, this review aims to provide insights into the reuse of various active ingredients in different types of distillers' grains, contributing to the reduction of carbon emissions and achieving a balance of economic, environmental, and social benefits worldwide.</p>