Mastitis is a prevalent disease in dairy cattle that indirectly reduces milk yield and quality. Post-milking teat dipping is an effective strategy to minimize its spread and severity. This study evaluated the antibacterial activity of Sterculia quadrifida R. Br. bark extract and its potential as a natural post-milking teat-dipping solution. Faloak bark collected from Kupang was extracted using 96% ethanol, followed by the determination of total phenolic and flavonoid contents. Antibacterial activity against mastitis-causing bacteria was assessed using the disc diffusion method with extract concentrations of 5%, 10%, 20%, 30%, 40%, and 50%. California mastitis test (CMT), somatic cell count (SCC), and total plate count (TPC) analyses were performed to compare its effectiveness with a commercial teat-dipping product using eight dairy cows with subclinical mastitis. Faloak bark contained 117.476±0.521 mg GAE/g phenolic compounds and 374.596±0.971 mg QE/g flavonoids. A 30% extract showed inhibitory activity against Staphylococcus aureus (10.7±0.3 mm), comparable to the commercial teat dip (10.8±0.8 mm). A 5% extract inhibited Streptococcus agalactiae (10.68±0.18 mm), while a 20% extract was more effective than the commercial teat dip against Escherichia coli (11.1±0.7 mm). No significant differences (P>0.05) were observed in CMT, SCC, and TPC values before and after teat-dipping treatment. However, the teat-dipping treatment lowered the CMT, SCC, and TPC test results. These findings suggest that faloak bark extract could be used as a natural antibacterial agent against mastitis-causing pathogens and as an alternative to teat dipping solutions.