OBJECTIVE This study aimed to investigate the effects of essential oil coated with glycerol monolaurate (GML) on the growth performance, intestinal morphology, and serum profiles of weaned piglets. METHODS A total of 144 weaned piglets (Duroc×[Landrace×Yorkshire], average weight 8.07±3.33 kg) were randomly assigned to three groups with six replicate pens and eight piglets per pen: i) CON: a corn-soybean basal diet; ii) LEG: with 1,000 mg/kg essential oil coated with GML; and iii) HEG: with 2,000 mg/kg essential oil coated with GML. RESULTS Results showed that average daily gain was increased (p<0.05) linearly by essential oil coated with GML supplementation on day 14 to 28 and day 0 to 28 compared with the CON group. Dietary supplementation with HEG increased (p<0.05) total antioxidant capacity and catalase activity on day 14, and immunoglobulin A (IgA) and IgM concentration on day 28 and tended to increase IgG on day 28. In addition, the crypt depth in the jejunum was reduced (p<0.05), and villus height and villus height/crypt depth in the ileum were increased (p<0.05) in the HEG group compared with the CON group. Moreover, lower (p<0.05) concentrations of tumor necrosis factor-α, interferon-γ, interleukin-1β (IL-1β), IL-8, and IL-10 were observed in the jejunum of piglets supplemented with HEG compared with the CON group. In addition, dietary HEG tended to decrease IL-6 level in the jejunum of piglets compared with the CON group. CONCLUSIONS Dietary essential oil coated with GML can improve growth performance of weaned piglets. Moreover, supplementing 2,000 mg/kg essential oil coated with GML was demonstrated to improve antioxidant ability, and intestinal morphology, and reduce jejunal inflammatory factor levels.