Aims: Senna siamea has various medicinal functions but specific studies pertaining to the antioxidant and antibacterial potential that are related to ultrasound-assisted extraction from S. siamea have not been found to be reported yet. Therefore, this research was to determine antibacterial activities and antioxidant of S. siamea leaf extracts using solvent extraction and ultrasound-assisted extraction. Methodology and results: Antibacterial activities were tested using the disc diffusion method and MIC and MBC values of seven bacterial strains. The ultrasound-assisted extraction extract had a higher yield, total phenolic content, antioxidant activities, and antibacterial activity than solvent extract. Interestingly, the strains of Staphylococcus sp., Vibrio parahaemolyticus, Escherichia coli, and Salmonella enteritidis were not inhibited by the solvent extracts, but were significantly (p < 0.05) inhibited by the ultrasound-assisted extraction extracts. Besides, the MIC and MBC values of extracts from ultrasound-assisted extraction were lower than the extracts from solvent extraction. Conclusion, significance and impact of study The results revealed that extracts from ultrasound-assisted extraction have higher efficiency to treat bacterial strains due to the efficiency of extraction method towards the recovery and solubility of extractable compounds. The results concluded that the extracted using ultrasound-assisted extraction can be used as active pharmaceutical components for the treatment, prevention, and control of pathogenic bacteria, including to be applied as food ingredients.