In this research, a micro carbon fiber electrode (MCFE) was activated using a simple flame annealing method and subsequently modified with mildly oxidized graphene oxide (M-GO) to develop an inexpensive and sensitive electrochemical sensor for dopamine (DA) detection. Observations indicate that flame annealing increases surface roughness, enhances electrochemical activity, and improves the electrode’s affinity for M-GO adsorption, resulting in a more sensitive DA sensor. The electrochemical properties and morphology of the modified electrode were characterized using electrochemical techniques, including cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), differential pulse voltammetry (DPV), and scanning electron microscopy (SEM). Electrochemical investigations revealed that the M-GO-modified flame-annealed micro carbon fiber electrode (FA-MCFE/M-GO) exhibits high sensitivity, a wide linear range, and a detection limit of 20 nM for DA determination. Another notable feature of this sensor is its ability to eliminate the interfering effects of uric acid (UA) during dopamine detection, which represents one of the primary challenges in the electrochemical analysis of DA in biological samples. The results demonstrate that using M-GO as a surface modifier for the carbon fiber microelectrode provides an effective and cost-efficient strategy for fabricating high-performance electrochemical sensors. This sensor shows substantial potential for diagnostic and clinical applications in measuring DA in the presence of interfering substances.