Acne is a skin disease that affects a large number of sufferers. Acne occurs due to active oil glands under the skin. This activity is stimulated by androgen hormones. The active compound content of proanthocyanidin is the main compound in the ethanolic extract of tamarind seed bark, which can inhibit the growth of acne-causing bacteria, namely Propionibacterium acnes and Staphylococcus epidermidis. The purpose of this study was to formulate a nanogel from tamarind seed bark extract and test the antibacterial potential of an ethanol extract of tamarind seeds against acne-causing bacteria. The antibacterial potency test consisted of variations in concentration and was 0.5, 1, 5, 25, 50, 75, 100, 125, 150, and 300 (in mg/mL). The concentration of the formulated nanogel preparations was 2.5%, 5%, and 7.5%. The MIC results showed that the minimum inhibitory concentration (MIC) was at a concentration of 1 mg/mL with a zone of inhibition of 6.50 ± 0.44 mm (Propionibacterium acnes) and 6.40 ± 0.10 mm (Staphylococcus epidermidis). The minimum bactericidal concentration (MBC) was at a concentration of 25 mg/mL with a percentage reduction of 98.18% (Propionibacterium acnes) and 98.06% (Staphylococcus epidermidis). The results of the nanogel formulations showed that the particle sizes were 49.88 ± 0.11 nm (Formula I), 51.92 ± 0.09 nm (Formula II), and 59.13 ± 0.10 nm (Formula III). Conclusion The ethanolic extract of tamarind seed bark has effectiveness in inhibiting the growth of acne-causing bacteria and can be formulated as an anti-acne nanogel.