The microbiome vagus brain axis is a dynamic and complex communication network that connects gut microbial populations and CNS function via vagally mediated pathways. To control mood, cognition, neuroinflammation, and systemic homeostasis, this bidirectional axis integrates neuronal, immunological, and endocrine inputs. The vagus nerve’s efferent fibres regulate immunological responses and GI physiology, while its sensory afferents carry microbial metabolites and neuroactive substances from the stomach to brain regions linked to emotional and cognitive processes. Disruptions in this axis, which are often brought on by gut dysbiosis, are linked to several neuropsychiatric and neurodegenerative conditions, such as depression, Parkinson’s disease, anxiety, and Alzheimer’s disease. Treatment strategies like vagus nerve stimulation and microbiome manipulation (e.g. probiotics, prebiotics, faecal microbiota transplantation) have been shown to improve neurological outcomes and restore a healthy gut-brain connection. However, problems like methodological heterogeneity, interindividual microbiome variability, and the translational gap between preclinical and human studies still persist. Future efforts will focus on identifying particular molecular pathways and maximising treatment success. Future efforts will focus on utilising advanced multi-omics and neurogenetic techniques, along with customised interventions, to identify specific molecular pathways and maximise treatment success. Understanding this intricate axis may revolutionise approaches to maintaining brain health and treating a range of CNS disorders by leveraging the microbiome’s influence on vagally mediated neuronal pathways.