In this study, we evaluated the antioxidant properties, phenolic contents, and flavonoids in C. coronarium L. flowers grown in Syria. Three flower extracts were prepared (aqueous extract, methanolic extract, and ethyl acetate extract), The results showed that ethyl acetate extract had the highest levels of phenols and flavonoids (5680 ± 11) and (2030 ± 8) mg/100g, respectively. The antioxidant test showed the strongest antioxidant capacity with ethyl acetate extract (81 ± 4%). In the antibacterial test, the difference in efficacy between the extracts was due to the difference in their ability to extract the active substances and the difference in the sensitivity of the bacterial strains to the active substances, where Gram-negative bacteria were less sensitive, especially E. coli.