The purpose of this study was to evaluate the bioactive compounds and antioxidant activity of extracts from araçá (Psidium cattleianum), butiá (Butia eriospatha), and pitanga (Eugenia uniflora) fruits with different flesh colors (i.e., purple, red, and orange), and blackberries (Rubus sp.; cv. Xavante and Cherokee) collected in the southern region of Brazil. The content of ascorbic acid, total carotenoids, and phenolics were determined. The profile of the phenolic compounds was assessed by high-performance liquid chromatography combined with diode array detection (HPLC-DAD). The antioxidant activity was determined using the ferric-reducing antioxidant power (FRAP) assay, 2,2-diphenyl-2-picrylhydrazyl hydrate (DPPH) assay, total reactive antioxidant potential (TRAP) assay, and total antioxidant reactivity (TAR) assay. The Xavante blackberry and purple-fleshed pitanga showed the highest total phenolic content [816.50 mg gallic acid equivalents (GAE)/100g and 799.80 mg GAE/100g, respectively]. The araçá and red-fleshed pitanga showed the highest carotenoid content (6.27 ug β-carotene/g and 5.86 ug β-carotene/g, respectively). The fruits contained several phenolic compounds such as quercetin derivatives, quercitrin, isoquercitrin, and cyanidin derivatives, which may contribute differentially to the antioxidant capacity. The highest scavenging activity in the DPPH assay was found for purple-fleshed pitanga (IC50 36.78 mg/L), blackberries [IC50 44.70 (Xavante) and IC50 78.25 mg/L (Cherokee)], and araçá (IC50 48.05 mg/L), which also showed the highest FRAP, followed by orange- and red-fleshed pitanga. Our results revealed that some fruits grown in southern Brazil such as purple-fleshed pitanga, blackberries, and araçá are rich sources of phenolic compounds and have great antioxidant activity.