Sargassum sp., cinnamon, and C. xanthorrhiza contain high polyphenols, which play an essential role in inhibiting α-glucosidase activity. The purpose of this study was to determine the optimization of the formula by mixing Sargassum sp. extract, cinnamon extract, and C. xanthorrhiza extract as functional beverages of α-glucosidase inhibitors. This research using the Response Surface Method (RSM) and Box-Behnken with a combination of three factors, namely the concentration of Sargassum sp. extract (A), the concentration of cinnamon extract (B), and the concentration of C. xanthorrhiza extract (C). The response variables consisted of total polyphenol (Y1), and percentage inhibition of α-glucosidase (Y2). The optimum formula was followed by UPLC-MS/MS assay. The best formulation for functional beverages is Sargassum sp. 20%, cinnamon 12.773%, and C. xanthorrhiza extract at 18.5% with of total polyphenols (108.834 mgGAE/100mL) and inhibition of α-glucosidase (64.323%).