This study investigates the antibacterial and antibioflm potential of quercetin against carbapenem and cephalosporinresistant clinical Escherichia coli and evaluating its antioxidant activity. E.coli- EI the most antibiotic-resistant strain was further employed in evaluating the antibacterial and antibioflm activity of quercetin. E.coli-EI preformed bioflm-biomass was eliminated by 53.1% when treated with quercetin (200 mg/mL). Additionally, SEM micrographs of treated bioflms showed elimination of most of the bioflm polysaccharide-matrix, decreased cell density, and cell membrane disruption of some bacterial cells. Furthermore, PCR and RT-qPCR results revealed downregulation of adrA bioflm gene. DPPH assay results indicated that quercetin dose-dependent antioxidant activity with IC₅₀ value of 53.06 mg/mL. Moreover, molecular docking studies revealed that quercetin is able to form several stabilizing interactions like hydrogen bonds and hydrophobic interactions, with AdrA-protein, displaying efective binding-capacity of -6.2 kcal/mol. Consequently, quercetin represents a natural feasible compound for treating E.coli infections in addition to its antioxidant competence.