The objectives of this study were to develop a symbiotic oat-based beverage (SOB) and to analyze its physiochemical properties and the probiotic survivability. The beverage base was prepared by fermenting a mix containing oat flour (10%, w/w), sugar (4%, w/w), and inulin (1%, w/w) with a commercial (0.003%, w/w) at 30 °C for 12 h. The SOB was formulated using the fermented oat base, sugar, stabilizers (pectin and λ-carrageenan), vitamin C, and citric acid. The beverage was analyzed for total solids (11.65 ± 0.22%), protein (0.58 ± 0.02%), fat (0.37 ± 0.02%), carbohydrate (10.70 ± 0.33%), ash (0.14 ± 0.01%), and dietary fiber (0.70 ± 0.05%). The pH value of the beverage was stable at about 3.60 during 7-week storage. population in the beverage remained above 10 CFU/g throughout the storage. Oat-based beverage is a low fat and high dietary fiber symbiotic food.