This study was designed to determine the preliminary phytochemical compounds, to study the potent bioactive compounds using GC-MS analysis and antioxidant potentials of Amaranthus hybridus and Amaranthus cruentus leaves after slicing, sun drying, and shade drying and cooking processing techniques. Ascorbic acid, total phenol content and antioxidant potential were determined by volumetric, Folin Ciocalteu reagent method and DPPH respectively. After preliminary screening for secondary metabolites evaluation, biochemical components where screened by GC-MS techniques. Results of phytochemical evaluation confirmed the presence of phytosterols, tannins, glycosides, saponins, flavonoids and terpernoids in both samples whereas alkaloids and anthraquinones were absent. Interestingly GC-MS analysis revealed the presence of fourteen compounds in A. cruentus and eighteen in A. hybridus. Phytol (39% and 40%) and 3,7,11,15-Tetramethyl-2-hexadecen-1-ol (13% and 17%) were the most abundant components in the two extracts. The total phenol content of SDS A. hybridus was significantly higher (p < 0.05) than that of any treatment of A. cruentus. SHDU of both samples revealed higher antioxidant activities and vitamin C content while cooking reduced drastically the Vitamin C content in both samples. In view of the results of this study, it could be concluded that various processing methods trough make green leafy vegetables more palatable by reducing some anti-nutrients content and extend their shelf-life. However they influenced on the phenolic content and antioxidant behavior and caused significant decrease (P < 0.05) in ascorbic acid contents of the green leafy vegetables. Combination of these leafy vegetables with others foodstuffs may be recommended to satisfactorily meet the RDA.