Glycated hemoglobin (HbA1c) is considered as the best biomarker that can indicate glycemic level over a prolonged period of time (two to three months). Since its level corresponds to the long-term progression of diabetes without short-term variation in the glucose behavior, it has been used to diagnose diabetes. Different methods are used for HbA1c quantification including high-performance liquid chromatography, immunoassays, and electrophoresis. Despite their analytical performance, these techniques are expensive and time-consuming. In this context, we have developed a simple electrochemical aptasensor for HbA1c detection. For that, a glassy carbon electrode surface has been modified by electrochemical deposition of AuNPs. Then, L-cysteine has been chemically deposited to allow the immobilization of amino-modified HbA1c aptamer via L-cysteine carboxylic groups. Due to the affinity interaction between HbA1c and its aptamer, the incubation of this sensor in the HbA1c solution leads to the formation of an AuNPs-L-cyteine-Aptamer-HbA1c complex. Chemical surface modification was characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Finally, the impedimetric detection of glycated hemoglobin was performed in presence of the redox active markers ferricyanide/ferrocyanide ions.