Gardenia obtusifolia, a traditional medicinal plant from Southeast Asia, was investigated for its phytochemical composition and bioactivity using methanol extracts and solvent-partitioned fractions from the leaves, fruit pulp, and rind. The plant material was authenticated morphologically and confirmed through matK gene analysis. Phytochemical screening revealed the presence of phenolic compounds, flavonoids, tannins, coumarins, and alkaloids. Among the fractions tested, the rind ethyl acetate fraction exhibited strong antibacterial activity against clinical pathogens, high phenolic content, and potent antioxidant capacity. GC-MS profiling identified key bioactive compounds, including vanillic acid, octadecane, and 5-hydroxymethylfurfural, which likely contribute to the observed bioactivities. Among the solvent fractions, the rind ethyl acetate fraction demonstrated strong anti-tyrosinase activity. This fraction consistently exhibited high phenolic content and potent antioxidant capacity, suggesting that these bioactivities are attributable to key phytochemicals known for antioxidant effects. Purification and GC-MS profiling identified bioactive compounds in the rind ethyl acetate fraction, revealing vanillic acid as a major contributor to antioxidant activity. G. obtusifolia shows great promise for application in the cosmetic industry as a natural ingredient for skin-whitening and anti-aging formulations. However, further in vivo and clinical studies are required, as in vitro results may not directly reflect clinical efficacy.