Recent research has highlighted the significant role of the gut microbiome in maintaining health and in the development of disease, including psychiatric disorders. Complex bidirectional communication between the microbiota, the community of microorganisms in the human digestive system, and the brain occurs via the gut-brain axis, involving neurological, metabolic, endocrine, and immune communication pathways, mediated by the vagus nerve, the hypothalamic-pituitary-adrenal axis, and immune mediators. The gut microbiota produces neuroactive metabolites, including neurotransmitters and their precursors, which can affect neuronal activity and cognitive brain functions. Disorders such as depression, schizophrenia, bipolar disorder, attention-deficit hyperactivity disorder, and autism spectrum disorders are associated with imbalances in gut microbiota and inflammatory processes. Regulation of gut dysbiosis through the use of probiotics and prebiotics is being investigated as a potential therapeutic approach to alleviate symptoms of these disorders. A better understanding of the complexity of interactions between the gut microbiota and the brain opens up avenues for personalized therapeutic approaches that could significantly improve how we approach and treat psychiatric disorders.