Abstract: The prolonged consumption of a high fat diet can cause not only the development of metabolic diseases such as obesity, type 2 diabetes mellitus, cardiovascular disease but also cognitive decline. The commensal microorganisms in human gut are called the gut microbiota. The composition of gut microbiota is associated with diet; consumption of a high fat diet changes the healthy microbiota composition which leads to an imbalanced microbial population in the gut, a phenomenon known as gut dysbiosis. It has recently been proposed that gut dysbiosis is part of a mechanistic link between high fat diet and the impaired cognition of an individual, termed microbiota-gut-brain axis. This review summarizes the relationship between high fat diet, gut microbiota and cognition, and the possible mechanisms underlying the effects of high fat diet and the gut microbiota on cognition.