ABSTRACT This study investigated the prebiotic potential of by-products from Puçá (Mouriri elliptica Mart) and Gabiroba (Campomanesia adamantium (Cambess.) O. Berg) (PBP and GBP). The fermentative capacity of Lactobacillus acidophilus LA-05, Lacticaseibacillus casei L-26, and Bifidobacterium animalis subsp. lactis BB-12 was evaluated on PBP and GBP extracts. Their prebiotic activity scores were evaluated in the presence of two strains of Escherichia coli. PBP and GBP contain high levels of dietary fiber and significant content of phenolic compounds such as catechin and procyanidin B2. Probiotic cultivation in media with PBP and GBP showed increased bacterial counts and decreased pH values. Positive probiotic activity scores were found for all strains, such as increased production of short-chain fatty acids and consumption of glucose and fructose over time, indicating high metabolic activities. Therefore, the PBP and GBP have characteristics that indicate their prebiotic potential, and potentially are interesting components to increase the nutritional value of foods.