Enriched melatonin (MEL) has been found in the mammalian intestine and has been recently demonstrated to alleviate rodent colitis. In this study, the effect of MEL on lipopolysaccharide (LPS)-induced intestinal inflammations was investigated in new chicken hatchlings. The chicks were fed with a diet supplemented with MEL (12.5 mg/day) from D1 to D10. Meanwhile, the chicks in the LPS or MEL + LPS groups were injected with LPS (10 mg/kg BW, i.p.) at D10. LPS treatment for 6 h increased the expression of IL-6, IL-4, caspase-3 mRNAs and TUNEL-positive cell populations, but decreased populations of the goblet and PCNA+ cells, IgA production and the expression of MUC2 mRNA in the duodenum. Compared with the LPS group, MEL pre-feeding alleviated duodenal inflammation and decreased the expression of TNF-α mRNAs by 23.6% (P = 0.004), IL-6 mRNAs by 69.4% (P = 0.001), IL-4 mRNAs by 4.1% (P = 0.824) and caspase-3 mRNAs by 45.8% (P < 0.001). Conversely, MEL pre-feeding attenuated the LPS-induced changes of IgA production by 161.6% (P = 0.013) and PCNA+ cell populations by 172.1% (P < 0.001) in the duodenum. TLR4 mRNA was also up-regulated by LPS treatment but down-regulated by MEL pre-feeding. In conclusion, dietary MEL could attenuate LPS-induced chick duodenal inflammation by down-regulating the expression of inflammatory cytokines, promoting epithelial cell proliferation, improving the immunological barrier and inhibiting epithelial apoptosis via the mediation of TLR4.