The United Nations’ 2030 Agenda has the objective to promote sustainable development, eradicating hunger and ending all forms of malnutrition. Industry coproducts, such as whey and buttermilk, can be used to increase functional, nutritional and technological aspects of foods and contribute to sustainable development. The use of exotic fruits with functional characteristics has also gained attention on food market, and cagaita, a Brazilian Cerrado fruit, has gained attention due its antioxidants properties. The aim of this work was the development and characterization of different formulations of whey-fermented beverages with buttermilk and cagaita pulp (Eugenia dysenterica). Using simplex-centroid mixture design, 7 formulations were defined with different concentrations of whey/buttermilk mix (W/B) between 30- 44%, milk (M) between 36 and 50% and cagaita pulp (C) between 6 and 20%. Physico-chemical and microbiological characteristics were determined by official methods. The results were evaluate by ANOVA and Pearson correlation test and mean values were compared by Scott-Knott’s test (P < 0.05). Beverages presented moisture between 80.50 and 82.81%, ash between 0.47 and 0.67%, protein between 1.59 and 2.00%, lipids between 1.18 and 2.70%, carbohydrates between 13.37 and 15.32% and total energy value between 72.75 kcal and 85.01 kcal, pH 3.96 and 4.47, acidity was between 0.36 and 0.58%. Milk concentration shows positive correlation with protein and lipids whereas W/B mixture shows negative correlation, therefore beverages with higher W/B and lower M had the lowest protein and lipids. The higher W/B and C, the higher moisture of beverages. All beverages had LAB content above 6 log₁₀cfu/mL and, for Salmonella spp. and coliforms, the beverages were within the Brazilian law standard and for food safety. The developed products presented expected physico-chemical and microbiological characteristics and were safe for consumption. Besides, these beverages are low cost dairy foods, by using dairy industry coproducts and still have functional characteristics conferred by whey, buttermilk and cagaita pulp.