BackgroundStress, herd transfer, and food changes experienced by nursery and fattening pigs can lead to reduced performance, reduced digestion and absorption, and impaired intestinal health. Given the role of essential oils in relieving stress and improving animal welfare, we hypothesized that essential oils may improve pig performance via promoting gut health and gut homeostasis laid by EOs supplementation during nursery continuously impacts performance in fattening pigs.ResultsA total of 100 piglets (Landrace × Large White; weighted 8.08 ± 0.34 kg, weaned at d 28) were randomly selected and divided into 2 treatments: (1) basal diet (Con); (2) basal diet supplement with 0.1% complex essential oils (CEO). The experiment period was 42 days. Then weaned piglets’ growth performance and indications of intestinal health were assessed. Compared to the Con group, dietary supplemented CEO enhanced BW at 14 d (P< 0.05), and increased ADG during 1 ~ 14 d and 1 ~ 42 d (P< 0.05). Furthermore, CEO group had lower FCR during 1 ~ 42 d (P< 0.05). The CEO group also showed higher VH and VH:CD in duodenum and ileum (P< 0.05). Additionally, dietary CEO supplementation improved gut barrier function, as manifested by increased the mRNA expression of tight-junction protein and decreased serum DAO, ET and D-LA levels (P< 0.05). Finally, CEO supplementation alleviated gut inflammation, increased the activity of digestive enzymes. Importantly, piglets supplemented with CEOs during nursery also had better performance during fattening, suggesting that the establishment of intestinal health will also continuously affect subsequent digestion and absorption capacity. In short, dietary supplemented CEO improved performance and gut health via modulating increased intestine absorptive area, barrier integrity, digestive enzyme activity, and attenuating intestine inflammation. Meanwhile, essential oil supplementation during the nursery period also had a favorable effect on the performance of growing pigs.ConclusionsTherefore, the strategy of adding CEO to pig diets as a growth promoter and enhancing intestinal health is feasible.Supplementary InformationThe online version contains supplementary material available at 10.1186/s40813-023-00317-x.