Heat stress poses a significant challenge to the ruminant livestock industry under the context of global warming, severely impacting animal production performance, immune function, and reproductive efficiency. Chromium, as an essential trace element for animals, plays a key role in regulating glucose and lipid metabolism, enhancing antioxidant capacity, and maintaining immune function. This review summarized the detrimental effects of heat stress on ruminants and its underlying mechanisms, and introduced the sources, types, and application effects of chromium under heat stress conditions. It focused on the ameliorative effects of chromium supplementation on the lactation performance, growth performance, and reproductive performance of ruminants. Furthermore, the review explored the mechanisms of action, including enhancing insulin sensitivity, regulating glucose metabolism, improving antioxidant capacity, boosting immune function, and modulating the rumen microbiota. This review also analyzed existing research limitations, such as insufficient comparability among different chromium sources and the lack of standardized dosage, and proposed future research directions, aiming to provide a theoretical basis and practical reference for alleviating heat stress in ruminants.