The objective of this work was to evaluate the effect of Beauveria bassiana (Bb 1205) on controlling Fusarium oxysporum f. sp. lycopersici (Fol 17108) in tomato plants in greenhouse conditions. Inoculation of Bb 1205 was the most promising among the agronomic variables and expression of the activity of the enzymes β-1,3-glucanases and chitinases. Inoculation of Bb 1205 occurred at a concentration of 1 × 10 8 conidia•mL −1 , which was administered onto the leaves, directly into the soil and via injection. Infection with Fol 17108 occurred with 1 × 10 6 spores•mL −1 , which were added directly to the soil. Spectrophotometry was used for measuring agronomic parameters, namely activity of chitinases and β-1,3-glucanases in foliage and roots. When Bb 1205 was added to the soil, the chlorophyll index and aerial part length showed significant differences. In addition, it was determined that root length, fresh weight of foliage, flower, and fruit count increased 82 days after inoculation (dai). Chitinase activity induced by Bb 1205 in leaves and roots of tomato plants infected with Fol 17108 was observed when injected into the stem at 32 dai (41.8 and 11.6-fold, respectively). Inoculation on the foliage showed a 10-fold increase of β-1,3-glucanases in the roots after 82 dpi. As for leaves, a 3.8-fold increase was found when the stem was inoculated. In the different in vivo applications, Bb 1205 activated its defenses by expressing the chitinase enzymes and β-1,3-glucanase, thus reducing the damage caused by Fol 17108, demonstrating increase plant growth thereafter.