Ethulia conyzoides is a plant traditionally used in managing diabetes in Nigeria. Unfortunately, its antidiabetic potential has not been scientifically examined. The research investigated the phytochemical constituents, in vitro antioxidant, and antidiabetic efficacies of E. conyzoides leaves extract. Seventy percent methanol extraction of E. conyzoides leaves was done to obtain its crude extract. It then was partitioned with n-hexane and ethyl acetate to obtain three fractions (n-hexane, ethylacetate and residual aqueous). Then, they were subjected to various phytochemistry investigations: 1,1-diphenyl 2-picryl hydrazyl (DPPH) radical scavenging activity assay and in vivo antidiabetic effects in mice. The fasting blood glucose (FBG) levels, weight change, feed and fluid intakes were determined using standard procedures. Phyto-profiles tests for the extract and its fractions revealed the presence of phenolics, tannins, cardiac glycosides, saponins and alkaloids. The result showed that the residual aqueous fraction had the nearest inhibitory concentration (IC50) of 0.011µg/ml to the standard ascorbic acid with 0.010µg/ml compared with other extract and fractions. There was a substantial (p < 0.05) rise in fluid and feed intakes and serum levels of FBG in the type 2 diabetic mice. Treatment of the mice using 100 mg/kg b.w. residual aqueous fraction for 21 days significantly (p < 0.05) reduced the fluid intake, feed intake and FBG and statistically (p < 0.05) improved the body weight. This study revealed that the residual aqueous fraction of E. conyzoides has antioxidant and antidiabetic activities against induced type 2 diabetic mice. Keywords: Antioxidant, Ethulia conyzoides, Fasting blood glucose, Phytochemical, Type 2 diabetes