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Tea tree oil is an essential oil of Melaleuca alternifolia which has antibacterial activity. Hydrophobic properties of tea tree oil cause problem in the formulation of drug product as well as water-based cosmetics. This study aims to formulate tea tree oil into nanoemulsion gel dosage form and evaluate its physical stability and antibacterial activity. Nanoemulsion gel was formulated in various concentrations of tea tree oil, which were 5%, 7%, and 9% using tween 80 as surfactant and propyleneglycol as cosurfactant. Nanoemulsion gel tea tree oil showed stable physical appearance during 8 weeks of storage at low temperature (4°C ± 2°C) and room temperature (25° ± 2°C), cycling test, as well as mechanical test. The best formula is nanoemulsion gel F1 containing 5% tea tree oil because it has good stability, smaller globule size, and more viscous. Results of antibacterial activity in vitro studies showed that tea tree oil nanoemulsion gel had antibacterial activity against Propionibacterium acnes by the formation of inhibition zone. Higher concentration of tea tree oil in nanoemulsion gel (5%, 7%, and 9%) showed greater mean inhibition zone (28,33 ± 0,88 mm; 30,33 ± 0,33 mm; and 31,67 ± 0,33 mm).