Research on finding new therapeutic drug for antioxidant, anticancer, antidiabetic is need of hour through natural products and exploring phytoconstituents to add up in the medicinal chemistry to study in detail and expel their various other properties. The current work emphasize on ornamental plant Euphorbia milii leaves to determine biological properties and phytoconstituents in methanol extract. To investigate the antioxidant activity, DPPH free radical scavenging assay was carried out, for anticancer property using MTT (3-(4, 5-dimethythiazolyl 21-2 5-dphenyttetrazolum bromide) in vitro cell proliferation assay was used, for antidiabetic studies used Alpha-amylase inhibitory assay was applied and also screening phytoconstituents in Euphorbia milii leaves methanolic extract. The anticancer activity found potent in in vitro proliferation MTT assay using A375 human melanoma cell lines by showing IC50 value 199.45µg/ml when compared to that of Cisplatin standard. Antidiabetic studies carried out by α-amylase inhibitory assay and found potent by showing IC50 value 171.28 µg/ml and in antioxidant activity was assessed by DPPH and found potent by showing IC50 value 63.06 µg/ml. These biological properties were due to rich phytochemicals in the methanolic extract positive for glycosides, alkaloids, steroids, flavonoids, phenols and saponins. The investigation concludes that E. milii leaves exhibited very good anticancer, antidiabetic, and antioxidant activities which are highly appreciable and further studies by pure molecule isolation and characterization may use it as novel biological remedies against various diseases.