Anxiety is a multifactorial pathology associated with oxidative stress and changes in different neurotransmitters in the central nervous system (CNS). Sarcomphalus joazeiro (Rhamnaceae) has a predicted effect on the CNS, being considered an alternative for pre-clinical investigations of anxiolytic drugs. The objective of this study is to evaluate the chemical composition, analyze the antioxidant capacity and the anxiolytic effect of the ethanolic extract of S. joazeiro leaves (EEFSJ) in zebrafish. The chemical profile was analyzed by liquid chromatography coupled to mass spectrometry (UPLC-PDA-ESI-QDA). Antioxidant action by DPPH• elimination and ABTS•⁺ capture assays. The 96 h acute toxicity and open field and light and dark tests, for sedative and anxiolytic evaluation, respectively, were applied in vivo, using zebrafish. It was possible to identify 11 compounds from the flavonoid and saponin class. EEFSJ exhibited a mean inhibitory concentration (IC50) of 185.2 ± 2.2 µg/mL and 74.17 ± 1.5 µg/mL against the DPPH• and ABTS•⁺ radicals, respectively. In vivo, EEFSJ demonstrated reduced locomotor activity and an anxiolytic effect similar to diazepam via GABAergic systems, without presenting toxicity within 96 h. These results suggest the safety of using EEFSJ for the development of clinical trials for the production of new anxiolytic drugs.