Arabinoxylans (AXs), the primary hemicellulose found in cereals and grasses, play a crucial role in regulating immunity, metabolism, and various physiological processes underscoring their value as essential components in dietary nutrition. Considering the extensive research on AXs in piglet nutrition, this paper systematically reviews their impacts on gut health and microbiota in piglets, as well as the underlying mechanisms of action. AXs have been shown to mediate gut barrier fortification through tight junction protein upregulation and orchestrate mucosal immunity homeostasis, consequently ameliorating early-weaning-associated diarrheal pathogenesis in piglets. Additionally, AXs function as microbial ecological modulators through selective enrichment of beneficial commensal microbiota (e.g., Bifidobacterium spp. and Lactobacillus spp.), while simultaneously stimulating microbial biosynthesis of short-chain fatty acids and ferulic acid exhibiting potent antioxidant and anti-inflammatory activity, thereby maintaining the intestinal health of piglets. This review offers valuable insights into their potential as a dietary intervention to support gut health and immune function in early-weaned piglets. However, most studies focus on single-source AXs such as wheat or corn, with limited exploration of novel sources or comparative effects of source combinations. Future research should systematically investigate the molecular mechanisms of AXs action, provide data-driven guidance for selecting AXs sources in feed formulations, and establish optimal inclusion levels in practical feeding regimens. Such efforts will further solidify the precision nutrition potential of AXs in promoting sustainable and healthy growth in piglets.