Moringa oleifera decoction is believed to alleviate gastrointestinal tract diseases. This study investigated antioxidant and anxiolytic activities of its leaves aqueous extract on acetic acid-induced colitis in rats. Rats (36) were randomly divided into six groups and received (20 days) distilled water, 10 mL/kg; Moringa oleifera leaf-aqueous extract (25, 50, and 100 mg/kg) or Loperamide (5 mg/kg). On days 1, 8, 17, and 20, behavioral parameters were evaluated. Colitis was induced (day 15, except in normal group) through acetic acid (4%, 1 mL) intra-rectal administration. After sacrifice (day 21), lesion number, weight/length ratio of the colon were recorded. Oxidative stress biomarkers were evaluated. On day 20, Moringa oleifera (100 mg/kg) reduced the number of head dipping and the duration in opened arms, respectively 2.00 ± 0.37 and 5.00 ± 0.37 s against 14.50 ± 0.72 and 2.17 ± 0.48 s in the control. It decreased colon weight/length ratio: 112.29 ± 9.46 against 185.93 ± 5.28 mg/cm in the control; malondialdehyde level (P < 0.01) and nitric oxide concentration (P < 0.001), in the brain: respectively 25.60 ± 0.60 and 36.34 ± 1.19 against 34.00 ± 0.33 and 46.17 ± 3.25 µmol/mg of tissue in the control. In the serum, the extract (50 mg/kg) significantly (P < 0.05) increased the catalase activity (0.10 ± 0.00 against 0.03 ± 0.00 µmol/mg of protein in the negative control group). At 100 mg/kg, it increased (P < 0.001) reduced glutathione concentration to 5.07 ± 0.31 against 3.26 ± 0.08 µmol/mg of protein in the negative control group. The improvement on colitis pathophysiology, the antioxidant and the anxiolytic effects noted therefore suggest that Moringa oleifera can be a potential source of drugs alleviating anxiety and oxidative stress associated to ulcerative colitis.