The present study aims to determine the bioactive compounds and biological activities of the Silybum marianum ethanolic extract (SME). Also, the potential effects of SME on obesity and other related complications in rats will be investigated. Data of the proximate chemical composition of Silybum marianum seed powder indicated that carbohydrates were the largest compound (67.21%) followed by ash (16.23±1.14%), crude fat (26.72%), Total protein (22.17%), crude fiber (7.17%) and ash (2.83%). Also, bioactive compounds content of SME indicated that Silymarin was the most largest compound (269.65 mg. g-1) followed by phenolics (127.65 mg gallic acid equivalent. g-1), flavonoids (65.1 mg quercetin equivalent. g-1), tannins (39.49 mg catechine equivalent. g-1), α-tocopherol (27.43 mg. g-1), chlorophyll (11.54 mg. g-1), β-carotene (6.83 mg. g-1) and anthocyanin's (4.29 mg Cyanidin 3-glucoside, CCy3G equivalent. g-1). The samples also exhibited several high biological activities which include inhibition of low density lipoprotein (LDL) oxidation and scavenging of free radicals. Such important biological effects could play important roles in strategies to combat/treat obesity and its complications in rats. SME intervention by 200 to 800 mg/kg bw/day by oral gavages for 8 weeks consecutive days leads to significantly (p≤ 0.05) decrease the body weight, lower the serum lipid profile parameters (TGs, TC and LDL-c), enhanced the liver functions in obese, and positively manipulate of the obesity-related the histopathological changes of the model (obese) control group. Therefore, data of the present study recommended like of that Silybum marianum extracts to be included in our daily diets, drinks, food supplementation and pharmacological formulae for the obese patients.