The ora-pro-nóbis (Pereskia aculeata Miller) is a cactus popularly known as “poor man's meat” due to its popular use related to the protein content found in its leaves and its low cost, thus being classified as an Unconventional Food Plant (UFP). The plant is recognized for the high nutritional value of their leaves, and it can be used in cooking and folk medicine. However, studies on the chemical characteristics and antioxidant capacity of ora-pro-nóbis fruits are scarce. This study aimed to evaluate the antioxidant potential and phenolic compounds of the stem and leaf flours and fruit pulp of P. aculeata Miller. The stem and leaves were washed and dried in a circulation oven at 60° ± 2 °C, and crushed in an industrial blender. The fruit was washed and macerated in natura, then hydroethanolic extracts were prepared. The content of phenolic compounds was evaluated using the Folin-Ciocalteau reagent and the results showed a total phenol content in the stem, leaves and fruits of 0.25; 1.01 and 118.2 mg EAG g-1 of extract, respectively. Antioxidants were evaluated using the DPPH method, obtaining values for stem, leaf and fruit of 1.20; 1.40 and 1.50 mg of fruit g-1 of DPPH respectively, and also by the ABTS method of stem, leaf and fruit of:13.82; 6.30; 3.20 µmol of Trolox g-1, respectively. Thus, P. aculeata Miller presented in its stem, leaves and fruits an expressive amount of phenolic and antioxidant compounds, being a potential resource to contribute to the prevention of several disorders associated with the production of free radicals as well as an alternative in the enrichment of foods and being a useful source for a food additive.