The study investigated the effects of microencapsulated essential oils (MEO) on the growth performance, diarrhea, and intestinal microenvironment of weaned piglets. The 120 thirty-day-old weaned piglets (Duroc × Landrace × Yorkshire, 8.15 ± 0.07 kg) were randomly divided into four groups and were fed with a basal diet (CON) or CON diet containing 300 (L-MEO), 500 (M-MEO), and 700 (H-MEO) mg/kg MEO, respectively, and data related to performance were measured. The results revealed that MEO supplementation increased the ADG and ADFI in weaned piglets (p < 0.05) compared with CON, and reduced diarrhea rates in nursery pigs (p < 0.05). MEO supplementation significantly increased the duodenum's V:C ratio and the jejunal villi height of weaned piglets (p < 0.05). The addition of MEO significantly increased the T-AOC activity in the jejunum of piglets (p < 0.05), but only L-MEO decreased the MDA concentration (p < 0.01). H-MEO group significantly increases the content of isobutyric acid (p < 0.05) in the piglet colon, but it does not affect the content of other acids. In addition, MEO supplementation improved appetite in the nursery and increased the diversity and abundance of beneficial bacteria in the intestinal microbiome. In conclusion, these findings indicated that MEO supplementation improves growth and intestinal health in weaned piglets.