This study was conducted to investigate the effects of dietary supplementation with different organic acid (OA) mixtures on growth performance, nutrient digestibility, and gut morphology in weaned pigs. A total of 56 weaned pigs (7.93 ± 1.04 kg body weight) were assigned to four dietary treatments with seven replicates per treatment for a 35-day study conducted over two phases: phase 1 (day 1 to 14) and phase 2 (day 14 to 35). Diets consisted of (1) a corn–soybean meal basal diet without any additive (negative control, NC); (2) NC + formic and propionic acids (TRT1); (3) NC + butyric, formic, and propionic acids (TRT2); and (4) NC + antibiotic (positive control, PC). During the overall period, the gain to feed ratio of pigs fed the PC and TRT1 diets tended to be higher (P = 0.059) than that of those fed the NC diet. However, OA supplementation had no effects on nutrient digestibility. Jejunal villus height to crypt depth ratio was higher (P < 0.05) in pigs fed the TRT1 diet than those fed the NC diet. In conclusion, dietary OA supplementation tended to increase overall feed efficiency and improved gut morphology in weaned pigs.