One of the most important factors in preserving host health and well-being is the human gut microbiota. Prebiotics, which are dietary components that specifically promote the growth and activity of beneficial bacteria in the gut, have garnered increasing attention in recent times. Among these, inulin, a naturally occurring polysaccharide, has emerged as a prominent prebiotic candidate due to its unique properties and potential health benefits. This chapter provides a comprehensive overview of the current state of knowledge regarding inulin as a prebiotic and its intricate interactions with the gut microbiota. The processes behind inulin’s prebiotic action are then thoroughly examined, with an emphasis on how it can specifically encourage the growth of advantageous bacterial strains like lactobacilli and bifidobacteria. The impact of inulin on microbial diversity, community structure, and functional metabolism within the gut ecosystem is discussed, emphasising its potential to modulate the balance between health-promoting and pathogenic microorganisms. Furthermore, the chapter explores the diverse physiological effects of inulin on the host. Special attention is given to the emerging evidence linking inulin consumption to improvements in metabolic health, inflammation, and the prevention of gastrointestinal disorders. In conclusion, the chapter consolidates current knowledge on the multifaceted roles of inulin as a prebiotic and its profound influence on the composition and functionality of the gut microbiota. Understanding these intricate interactions provides valuable insights into the potential therapeutic applications of inulin in promoting gut health and preventing associated diseases, paving the way for future research directions and clinical interventions in the field of microbiome-targeted nutrition.