Abstarct: In the first part of this dissertation, a glassy carbon electrode (GCE) was modified using the food dye Sunset Yellow (SY) to develop a simple, environmentally friendly, and cost-effective electrochemical sensor. The performance of this modified electrode as a sensor for the simultaneous and selective determination of ascorbic acid (AA), dopamine (DA), and uric acid (UA) was demonstrated. SY was covalently immobilized onto the electrode surface. The structure and morphology of the modified electrode were investigated using field-emission scanning electron microscopy (FESEM), which confirmed the presence of SY particles on the glassy carbon electrode surface. The electrochemical activity of the modified electrode was evaluated using cyclic voltammetry (CV), chronoamperometry, chronocoulometry, and electrochemical impedance spectroscopy (EIS). The results showed that under optimized conditions, the SY/NaOH-modified electrode exhibited excellent electrocatalytic activity, a suitable linear range (320–7, 45–0.2, and 50–0.2 µM), low detection limits (4.78, 0.12, and 0.12 µM) for AA, DA, and UA, respectively, and high stability. The analytical applicability of the SY/NaOH-treated GCE was successfully assessed for the determination of AA, DA, and UA in real samples such as bell pepper, grapefruit, dopamine ampoules, vitamin C tablets, tap water, and biological samples (human blood and urine). In the second part, the simultaneous electrochemical determination of three synthesis food dyes, including Ponceau 4R (PON), its isomer Amaranth (AMA), and Tartrazine (TAR), was performed using an electrochemical sensor baxsed on poly-Sunset Yellow and multi-walled carbon nanotubes. In this research, Sunset Yellow was polymerized using an innovative electropolymerization process. FESEM analysis confirmed that the multi-walled carbon nanotube surface was coated with a polymer laxyer of Sunset Yellow. The electrochemical activity of the sensor was validated using EIS, CV, and chronoamperometry. Under optimized experimental conditions, the electrochemical determination of PON, AMA, and TAR was carried out using differential pulse voltammetry (DPV). The results demonstrated that the developed sensor exhibited low detection limits (LOD) of 0.11, 0.21, and 0.13 µM and a linear range of 0.50–30.0 µM for PON, AMA, and TAR, respectively. The applicability of this developed sensor for routine analysis of real samples was successfully demonstrated by determining PON, AMA, and TAR in jelly, jelly belly candies, and tap water.