The poultry industry faces significant annual financial losses due to heat stress, which also poses risks to the health and wellbeing of the birds. including other animals, chickens that are exposed to high ambient temperatures have a variety of physiological changes. These include behavioral changes including stopping to eat, the start of a stress signaling cascade, and immunological and inflammatory reactions in the intestines. The neurological and humoral systems connect the brain and gut, facilitating two-way communication. This network is referred to as the gut-brain axis. Furthermore, heat stress modifies the makeup and abundance of the microbiome in addition to causing hyperthermia and oxidative stress at the gut epithelium, which reduce permeability and increase susceptibility to infection and inflammation. Similar routes are used by the gut microbiota to communicate and control host metabolic balance, health, and behavior. These pathways are mostly mediated by metabolites generated by bacteria as well as hormones and neurotransmitters. It follows that altering the gut microbiota's makeup will influence intestinal health and alter host brain circuits through a variety of complimentary and reinforcing ways. We outline the composition and operation of the microbiota-gut-brain axis in this review, focusing on the physiological alterations that transpire in chickens during heat stress.