The term gut-brain axis has risen as a critical research focus due to its far-reaching impact on human health, particularly in gastrointestinal and neurological conditions. This axis manifests a bilateral communication network linking the gut and the brain, regulated by gut microbiota through various pathways. These gut-residing microbes serve a vital role in regulating physiological processes, including immune responses, metabolism, gastrointestinal function, brain activity, and behavior. Accumulating data from numerous studies underscores the prospective role of the intestinal microbiota in cognitive functions, including memory, learning, and mood regulation, along with neurodevelopmental and neurodegenerative disorders. This has sparked growing interest in targeting the gut microbiota through nutritional and therapeutic strategies to enhance cognitive health and overall well-being. In this chapter, we aim to elucidate the intricate relationships of the microbiota-gut-brain axis, focusing on the biological interplay between the gastrointestinal tract and the brain. We explore how disruptions in this communication may be involved in neurological diseases and how the gut microbial metabolic products, including neurotransmitters and short-chain fatty acids (SCFA), influence fundamental neurodevelopmental and neurodegenerative processes. Furthermore, we review innovative therapeutic strategies—in particular probiotics, prebiotics, and fecal microbiota transplantation—formulated to modulate the microbiome, reinstating host-microbe homeostasis, and promote neurological health.