Neuroinflammation plays a central role in the development and progression of several neurological and neurodegenerative disorders. In recent years, increasing scientific evidence has demonstrated that the gut microbiota interacts closely with the immune system and the central nervous system (CNS) through a complex communication network known as the gut–brain–immune axis. This bidirectional system integrates neural, endocrine, metabolic, and immune signaling pathways that regulate brain function and systemic immune responses. Disturbances in gut microbial composition, commonly referred to as gut dysbiosis, have been linked to increased intestinal permeability, systemic inflammation, and activation of neuroinflammatory pathways. The present review aims to explore the structural and functional components of the gut–brain–immune axis and to summarize the molecular mechanisms through which gut microbiota influences neuroinflammatory processes and neurological disorders. A comprehensive literature review was conducted using major scientific databases including PubMed, Scopus, and Google Scholar. Relevant peer-reviewed articles, reviews, and experimental studies published in recent years were selected using keywords related to gut microbiota, neuroinflammation, immune signaling, and microbiome-based therapies. The selected studies were critically analyzed to identify key mechanisms and therapeutic developments. The findings suggest that gut microbiota significantly influences neuroinflammatory responses through multiple mechanisms, including microbial metabolite production, cytokine-mediated immune signaling, neuroendocrine pathways, and vagus nerve communication. Dysregulation of this axis has been associated with neurological conditions such as Alzheimer’s disease, Parkinson’s disease, multiple sclerosis, autism spectrum disorder, and major depressive disorder. Recent pharmacological research has focused on microbiome-targeted interventions such as probiotics, prebiotics, synbiotics, dietary modulation, and fecal microbiota transplantation. Additionally, natural compounds including curcumin, polyphenols, and adaptogenic herbs have shown potential neuroprotective and anti-inflammatory effects through modulation of gut microbial balance. Understanding the interactions between gut microbiota, immune signaling pathways, and neural mechanisms may provide novel therapeutic strategies for managing neuroinflammatory diseases. Targeting the gut–brain–immune axis therefore represents a promising direction for future pharmacological research and the development of innovative treatments.