Approximately 50% of Brazil nut weight and volume comes from its shell, which is a residue of its industrialization. The investigation of bioactive compounds from Brazil nut shell, such as phenolic compounds, is an alternative to add value to this byproduct. The aim of this study was to investigate free and bound phenolics content and the antioxidant capacity of Brazil nut shell. Free phenolics were extracted with acetone:water (40:60, v/v) and the bound phenolics with alkaline hydrolysis (10M NaOH), followed by acid hydrolysis (6N HCl). The extracts were analyzed spectrophotometricaly to determinate total phenolics content by Follin-Ciocalteau reagent assay (765 nm) and total flavonoids content by aluminum chloride assay (420 nm). Antioxidant capacity was determined by FRAP and TEAC assays. Brazil nut shell extracts showed the following values, respectively: 43.9 ± 1.37 mg GAE/100 g and 85.7 ± 1.42 mg CE/100 g, free phenolics; 141 ± 4.19 mg GAE/100 g and 115 ± 21.4 mg CE/100 g, phenolics freed by alkaline hydrolysis; and 8.41 ± 0.27 mg GAE/100 g and 8.37 ± 1.06 mg CE/100 g, phenolics freed by acid hydrolysis. The extracts showed expressive values of antioxidant capacity in the free (117 ± 1.95 mmol Fe+2/100 g, FRAP, and 85.9 ± 0.02 TE/100 g, TEAC), and bound fractions both after alkaline (41.9 ± 0.03 mmol Fe+2/100 g, FRAP, and 1595 ± 66.7 TE/100 g, TEAC) and acid hydrolysis (23.8 ± 0.10 mmol Fe+2/100 g, FRAP, and 32.9 ± 1.79 TE/100 g, TEAC). These results indicate that the majority of Brazil nut shell phenolic compounds were bound, especially by ester bounds, which were broken by alkaline hydrolysis. Therefore, the extraction of Brazil nut shell’s phenolic compounds, especially when preceded of hydrolytic reactions, can contribute to add value to this byproduct and foment processes to reduce its discard in the environment.