Abstract:[Objective] To investigate the effect of hesperidin (Hes) and rosmarinic acid (RA) combination on the growth performance and the cecal morphology, antioxidant function, microbiota, and barrier function of finishing pigs. [Methods] Twenty-four 90-day-old Duroc×Landrace×Yorkshire male pigs were randomly assigned to control (Con), Hes, RA, and Hes×RA groups (n=6). The Con, Hes, RA, and Hes×RA groups were given a basal diet, a basal diet supplemented with 600 mg/kg Hes, a basal diet supplemented with 40 mg/kg RA, and a basal diet supplemented with 300 mg/kg Hes and 20 mg/kg RA, respectively. The trial period was 90 d and divided into two stages: early fattening stage (1-40 d) and late fattening stage (40-90 d). [Results] Compared with the Con group, Hes×RA increased the average daily feed intake in the early fattening stage, late fattening stage, and whole period, increased the average daily gain in the early fattening stage and whole period, and decreased the feed/gain ratio in the whole period (P<0.05). Hes×RA increased the mucosal thickness, total antioxidant capacity (T-AOC), and superoxide dismutase (SOD) activity and up-regulated the relative mRNA levels of nuclear factor erythroid 2-related factor 2 (NRF2) and heme oxygenase-1 (HO-1) of cecum (P<0.05). The combination decreased the relative abundance of Proteobacteria, Terrisporobacter, Clostridium sensu stricto 1, and Romboutsia, increased the relative abundance of Bacteroidota,Lactobacillus, Muribaculaceae_norank, Phascolarctobacterium, and Rikenellaceae RC9, and increased the concentrations of isobutyrate and butyrate in the cecal digesta compared with the Con group (P<0.05). Furthermore, this combination up-regulated the relative mRNA levels of zonula occludens 1 (ZO-1), Claudin-1, and mucin-2 (MUC-2), reduced the content of interleukin-1β (IL-1β), and increased the content of secretory immunoglobulin A (SIgA) in the cecum (P<0.05) compared with the Con group. [Conclusion] The Hes×RA combination improved the growth performance and the cecal morphology, microbiota structure, antioxidant capacity, and barrier function of finishing pigs.