In this study, the antioxidant capacity of the peel and pulp of three Pitaya species was investigated: Hylocereus undatus, Selenicereus megalanthus, and Hylocereus polyrhizus. The methods used include the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging method, the thiobarbituric acid reactivity assay (TBARS) for inhibition of lipid peroxidation, and the Folin-Ciocalteau method for determination of total phenolic content. Regarding the TBARS results, the peel sample of 20% H. polyrhizus showed the highest antioxidant capacity in both solvents (water and alcohol) analyzed. Regarding the pulp, the H. undatus sample in the aqueous extract was the sample with the highest antioxidant potential (12.5%). In the ethanolic extract, the sample of H. polyrhizus pulp (25%) showed the highest antioxidant potential, as did the peel at a concentration of 20%. Using the DPPH method, the peel sample of the 5% aqueous extract of H. undatus can be highlighted with a greater antioxidant capacity. Regarding the pulp, the sample with the highest potential was the 20% H. undatus in the aqueous extract. In the ethanolic extract, the H. undatus samples from the peel and pulp showed the highest antioxidant potential with 25 and 50%, respectively. In terms of phenolic content, no significant difference was found between the peel samples, but among the pulp samples, H. undatus had the lowest concentration. It can be concluded that the different pitaya species exhibited significant antioxidant capacity, suggesting that pitaya consumption could potentially provide benefits to human health due to its bioactive compounds.