Background: Several countries have made an association that how conventional and traditional medicines support the rational use of medicinal plants in different treatments. Brazil has stimulated the cultivation of and the development of the studies of Libidibia ferrea, a plant with medicinal properties, which are provided by the presence of bioactive compounds in its several parts, such as fruits. The synthesis of these biomolecules may increase with Arbuscular Mycorrhizal Fungi (AMF) inoculation. However, there have been no previous reports about the optimization in the production of biomolecules in the fruits of mycorrhizal L. ferrea. Objective: The aim of this study was to define the potential advantages of inoculation with AMF by increasing the production of biomolecules and antioxidant activity in fruits of mycorrhizal L. ferrea. Methods: The phytochemical and mycorrhizal analyses occurred after 32 months of transplanting to the field and the plants were inoculated or not with Acaulospora longula, Claroideoglomus etunicatum and Gigaspora albida and then by transplanting the seedlings to the field. Results: Compared to those from the control treatment, the concentration of phenols and tannins in the fruits of L. ferrea inoculated with A. longula increased 26.4% and 39.8% (p <0.05), respectively. The fruits also had higher antioxidant activity. In contrast, the concentration of phosphorus in the fruits of L. ferrea inoculated with A. longula and C. etunicatum was not incresead. Because the concentration of phosphorus in fruits was verified in this study. Conclusion: Mycorrhization increased the concentration of biocompounds and antioxidant activity in the fruits of L. ferrea, which is of great interest to the herbal medicine industry.