Red dragon fruit and apple can be used as functional food because those natural product contain flavonoids and vitamin C which act as antioxidants. Antioxidants are needed by the body to prevent cell damage caused by free radicals. This study was aimed to determine the best formula with different amounts of red dragon fruit juice on each formula and determine the levels of flavonoids, antioxidant activity, and dietary fiber. There were 4 formulas that had been made, which were : Formula 1 (100 g apple pulp: 0 g red dragon juice), Formula 2 (100 g apple pulp: 50 g red dragon juice), Formula 3 (100 g apple pulp: 75 g red dragon juice), Formula 4 (100 g apple pulp: 100 g red dragon juice). Antioxidant activity was determined using 1,1-diphenyl-2-picrylhydrazyl (DPPH) method using UV-Vis spectrophotometry. The parameters measured in this study were panelist acceptance, flavonoid levels, antioxidant activity, and dietary fiber. The results of the analysis showed that formula 4 was the preferred formula by panelists because it had a higher hedonic average value compared to other formulas. Flavonoid content of formula 4 sheet jam was 0.0179%. The antioxidant activity of formula 4 sheet jam was classified as moderate with IC₅₀ of 126.97 ppm and dietary fiber was classified as high with 8.19% value.