Post-traumatic stress disorder often contributes to various anxiety-like behaviors. The single prolonged stress was used to induce anxiety-like behaviors of rats. In this model, using an elevated plus maze test, we observed that tangeretin treatment reversed the decrease in the number of open arms entries, the percentage of time spent in open arms with no change in the number of closed arms entries, and percentage of time spent in closed arms in rats subjected to single prolonged stress. Furthermore, in an open field test, tangeretin treatment reversed the decrease in the number of crossing and time spent in the center field with no change in the activities in the peripheral regions. Diminution in serotonin in different parts of brain of rats with post-traumatic stress disorder was reversed by tangeretin. At the molecular level, tangeretin treatment increased the expression of nuclear factor erythroid 2-related factor 2, heme oxygenase 1, and oxidoreductase-1 that was reduced in the post-traumatic stress disorder group in a dose-dependent manner. In conclusion, these studies have shown for the first time that tangeretin relieves anxiety-like behaviors in rats with post-traumatic stress disorder by activating nuclear factor erythroid 2-related factor 2 signaling pathway.