Xylooligosaccharides (XO) are emerging prebiotics obtained from crop residues or other lignocellulosic materials that are cheap and abundant in nature. XO improve gut health, nutrient digestibility, immune responses, and growth performance by selectively stimulating probiotic bacteria such as Bifidobacterium and Lactobacillus and thus promoting short chain fatty acid production in monogastrics such as swine, calves and chickens. In nursery piglets, XO supplementation reduced the occurrence of post-weaning diarrhoea. In laying hens, they improved egg yield, quality, and lipid metabolism; in broilers, they enhanced feed efficiency and reduction in mortality. In ruminants, XO supplementation increased fibre digestibility, milk yield, and utilization of metabolisable energy and lowering enteric methane emissions. In a nutshell, XO shown to support gut health, immunity, metabolism, and sustainability, highlighting their value as next-generation feed additives for animal production.