Breast cancer ranks the highest percentage of new cases and deaths in women worldwide. Problems that arise from cancer treatment with chemotherapy are non-selective and severe side effects. The flowers of rosella (Hibiscus sabdariffa L.) contain flavonoid compounds namely anthocyanin, one of which is cyanidin 3-O-glucoside. Previous research showed that roselle’s aqueous extract was able to inhibit MCF-7 breast cancer cell growth. This study aims to explore the antioxidant and cytotoxic abilities of n-hexane roselle fraction to T47D breast cancer cells. Roselle powder was extracted with 70% ethanol and followed by n-hexane fractionation to obtain N-Hexane Roselle Fraction (NRF). Identification of flavonoid compounds in the NRF using TLC method. The antioxidant ability of the NRF was analyzed using the DPPH method, in vitro cytotoxic tests on T47D breast cancer cells were carried out using the MTT assay method, followed by cell cycle testing with flowcytometry method. In silico test to determine the bond affinity between cyanidin 3-O-glucoside to HER2 and EGFR proteins was carried out by molecular docking method. The results of the identification of compounds showed that NRF contained flavonoids. NRF has a weak antioxidant ability with an IC50 value of 4259 μg/mL. NRF is quite toxic in T47D breast cancer cells with IC50 values of 213 μg/mL and is able to inhibit the T47D cell cycle in G2/M phase. Cyanidin 3-O-glucoside has a strong bonding affinity with HER2 and EGFR protein of -8.1 and -8.2 kcal/mol respectively.