Irritable Bowel Syndrome (IBS) is one of the commonest functional diseases affecting the digestive system. Recent research focuses on the interaction between the gut microbiome-serotonin axis and its role in the gut-brain axis. Serotonin (5-HT), produced primarily in the gut, regulates intestinal movements and secretion processes and provides sensory information about visceral stimuli. An imbalance in the gut microbiome causes abnormal levels of serotonin production, resulting in dysfunctions within the gastrointestinal tract. This article will look at various components of the gut microbiome and its role in health and disease, as well as the mechanism of serotonin production and function. Interventions based on the above knowledge can be used to manage patients suffering from IBS.