Garlic and onion are very important vegetables which are grown and consumed daily by all classes of the population in Ethiopia generally and Amhara region specifically. These vegetables serve as sources of vitamins and minerals in foods. Voltammetric techniques have been considered as important methods among the analytical techniques used for the identification and determination of trace concentrations of many biological molecules such as L-ascorbic acid. In this study, ascorbic acid content of freshly prepared and dried garlic and onion samples were determined and compared to each other and with literature values. Square wave voltammetry using glassy carbon electrode was used for electrochemical determination of ascorbic acid in the studied samples. Under the optimized conditions, the oxidative peak current showed linear dependence on the concentration in the range 0.05 – 2 mM with correlation coefficient (R2) of 0.99900 for Qoga onion, 0.9978 for Qoga garlic, 0.99747 for Gumara garlic, and 0.99948 for Gumara onion. Limit of detection of 6 x 10-10 mM, limit of quantification of 1.9 x10-9 mM and recovery results 98.96 and 99.83% of spiked ascorbic acid in freshly prepared garlic and onion samples validated the applicability of the method for the determination of ascorbic acid in the studied samples. While the ascorbic acid content of Qoga garlic and onion was found to be 28.24 and 7.39 mg/100 g, respectively; its content in Gumara garlic and onion was found to be 12.03 and 6.05 mg/100 g, respectively. Keywords: Ascorbic acid, cyclic voltammetry, square wave voltammetry, glassy carbon electrode, standard addition method, fresh and dry vegetables.