Detection of inflammatory and pro-inflammatory cytokines is of great importance due to their involvement in the pathogenesis of various health conditions. In this thesis, a highly sensitive electrochemical aptamer-based biosensor (aptasensor) is presented for precise and label-free detection of tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6). The aptasensor was fabricated based on a gold screen-printed electrode (GSPE) which was modified by electrochemically-deposited gold nanoparticles (AuNPs). The thiolatedaptamers were anchored on the surface of the aptasensor using gold-sulfur chemistry. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques were employed to characterize the aptasensor through the fabrication process. For measurement of target cytokines square wave voltammetry (SWV) was carried out in a redox electrolyte solution containing [Fe(CN)₆]^3-/4-. Based on the results, the aptasesnor was capable of detecting TNF-alpha and IL-6 in a linear range of 1 pg/mL to 1 μg/mL with a detection limit of 0.278 pg/mL. For IL-6 the linear detection range of the patasensor was 1 fg/mL to 1 μg/mL with a detection limit of 1 fg/mL. The label-free sensing scheme of the aptasensor and its simple fabrication procedure make it promising for point-of-care applications.