Ultraviolet radiation and exposure to environmental pollution can contribute to premature aging and skin cell damage. Teak leaves (Tectona grandis L.f.) are known to contain secondary metabolites, particularly flavonoids and phenolic compounds, which have the potential to exhibit antioxidant activity. This study aims to develop a loose powder formulation containing teak leaf ethanol extract and to evaluate its physical stability and antioxidant activity. The experimental study was conducted by formulating the extract at concentrations F0 (0%), F1 (15%), F2 (20%), and F3 (25%), followed by evaluations of physical quality, a cycling test, an irritation test, a hedonic test involving 30 panelists, and antioxidant testing using the DPPH method. The extract tested negative for ethanol and heavy metals but tested positive for alkaloids, flavonoids, tannins, and terpenoids. The extract’s antioxidant activity yielded an IC50 value of 69.02 ppm, which is classified as strong. All formulations met the requirements for physical quality, safety, and stability during the cycling test. The IC50 values for F0, F1, F2, and F3 were 253.75 ppm (weak), 107.90 ppm (moderate), 90.55 ppm (strong), and 75.64 ppm (strong), respectively, while the positive control (product X) was 69.80 ppm (strong). F3 (25%) was the formulation with the best antioxidant activity. The results of this study indicate that teak leaf ethanol extract has the potential to be used as an active ingredient in an antioxidant-active loose powder formulation.