Phytochemical screening is an important step which leads to the isolation of new and novel compounds. Plant Gossypium herbaceum plays a crucial role in folk medicine. The present study was conducted with the main objectives of qualitative, quantitative phytochemical analysis and evaluation of antioxidant properties methanolic leaf extract of G. herbaceum. Leaves of G. herbaceum was subjected to successive solvent extraction by continuous hot extraction (Soxhlet) with methanol. Results depicted that the major phytochemicals found in methanolic extract of leaves of G. herbaceum were found to be alkaloids, flavonoids, proteins & amino acids, reducing sugars, saponins, phenolic compounds/tannins, and terpenoids. Quantitative estimation of phytochemicals in methanolic extract of leaves of G. herbaceum revealed that total phenolic quantity was found to be highest (51.36 GAE) followed by total flavonoid (45.28 GAE), and Tannins (3.68 mg/mL). The IC50 values exhibited by methanolic extracts of leaves of G. herbaceum and standard ascorbic acid was found to be 39.44 µg/mL and 11.98 µg/mL respectively. In conclusion, biological activity such as antioxidant properties of methanolic extracts of leaves of G. herbaceum depicted that G. herbaceum could be potential drug agent of folk medicines.