Phyllanthus amarus Linn. (Family: Euphorbiaceae) is found in tropical and sub-tropical region of the world. It is being used for the treatment of severe microbially infected disorders. The present study quantifies the phytochemical constituents. The present study also evaluated the in vitro antioxidant and antimicrobial properties of aqueous and 70% ethanolic extracts of leaves of the plant. The total polyphenolic content of the water and 70% ethanolic extracts showed the amounts are 60.28 ± 0.05 and 59.58 ± 0.13 mg GAE/g DW and the total flavonoids content of aqueous and 70% ethanolic extracts showed the values 85.88 ± 1.77 and 95.15 ± 2.70 mg QE/g DW, and the total tannin content for aqueous and 70% ethanolic extracts 53.21 ± 0.6 and 40.91 ± 0.70 mg TAE/g DW, respectively. According to the result, aqueous extract showed more effective antioxidant and antimicrobial activity than ethanolic extract. The plant leaves possesses significant amount of phytochemicals which are effective in the treatment of many oxidative stress-related damages and microbial infections. Based on the present research investigation it may be concluded that Phyllanthus amarus can be used for the preparation of natural drugs for pharmaceutical and nutraceutical industries.