This study was conducted to manufacture a Bokbunja (Rubus coreanus) Kombucha by combining black tea liquor with Bokbunja sugar syrup and inoculating it with an Acetobacter sp. and Lactobacillus spp. The biochemical and antioxidant properties of the manufactured Kombucha were then investigated. Using response surface methodology (RSM), a total of 9 combinations of Bokbunja Kombucha were made using various combination ratios. These were then fermented to select the best antioxidant activity, acidity, and organic acid content. Fermentation was carried out with the best Bokbunja Kombucha mixture ratio, and the experimental values were compared with the antioxidant activity, acidity, and organic acid content of the predicted RSM values. Additionally viable cell count and total polyphenols were also measured. After fermentation, Bokbunja Kombucha contained acetic acid at 3,705.34 mg/100 mL, followed by lactic acid at 117.95 mg/100 mL. The total polyphenol content increased from 480.83 μg catechin equivalents (CE)/mL to 763.33 μg CE/mL, and the ABTS radical and DPPH radical scavenging activity decreased from 96.12% to 89.81% and 74.05% to 46.09%, respectively.