Sesbania grandiflora (L.) Poiret, which is a member of the Fabaceae family and is also known as Vegetable hummingbird, Agati, Katurai, or West Indian pea, has a variety of medicinal uses. As a result, the current study concentrated on phytochemical analysis and antioxidant assays (DPPH, ABTS, superoxide, and OH) of methanol, ethanol, and water extracts of the leaf. The present findings revealed that the highest total phenolic content was found in methanol extract (62.06±1.02 mg GAE/g) followed by ethanol (60.89±0.13 mg GAE/g) and water (61.87±1.96 mg GAE/g). The maximum flavonoid content was recorded in the methanol extract (74.32±1.02 mg catechin equivalents (CE)/g) followed by ethanol (72.05±1.02 mg CE/g) and water (60.44±1.05 mg CE/g). Similarly, the methanol extract (522.21±1.06 mg oleanolic acid equivalents (OAE)/g) showed the highest saponin content followed by ethanol (517.34±1.21 mg OAE/g) and water (450.21±0.75 mg OAE/g). Among four antioxidant assays used in the present study, the highest DPPH free radical scavenging was found in methanol leaf extract (91.22±1.45%) followed by ethanol (85.55±1.11%) and water extract (77.85±1.25%). The ABTS assay also showed maximum scavenging in methanol extract (88.45±1.32%) followed by ethanol extract (79.45±1.25%). The superoxide anion radical and hydroxyl radical scavenging assays also showed the highest activity in the methanol extract (90.12±1.12%) and the lowest (20.21±1.33%), followed by ethanol (85.55±1.26%) and lowest (15.56±1.34%), OH method main amount in methanol (88.95±1.21%) and lowest (20.12±1.46%), followed by ethanol (78.60±1.25%) and lowest (16.32±1.45%). Using ascorbic acid and quercetin as standards and calculated IC50 values, our research found that S. grandiflora leaf has potential medicinal qualities, and targeted chemicals can use in pharmaceutical and pharmacological aspects.