© 2021 Taylor & Francis Group, LLC.A novel electrochemical dopamine (DA) sensor based on Au nanoparticles (AuNPs) electrochemically loaded on poly([2,2′;5′,2″]-terthiophene-3′-carbaldehyde)/reduced graphene oxide (poly(TTP)/rGO) improved glassy carbon electrode (GCE) was fabricated. The Au@poly(TTP)/rGO/GCE was evaluated using cyclic voltammetry (CV), differential pulse voltammetry (DPV), amperometry, and electrochemical impedance spectroscopy (EIS). The optimized Au@poly(TTP)/rGO/GCE sensor had a wide electroactive surface area and exhibited good selectivity. The linear determination range of the sensor was from 0.02 to 232 µM with a sensitivity of 315 µA/mM/cm2. The limit of detection (LOD) was estimated to be 11.5 nM using signal-to-noise (S/N) ratio of 3. Additionally, the sensor displayed excellent selectivity, satisfactory response time from 4.5 to 6 s, replicability with a relative standard deviation (RSD) of 2.31%, reproducibility with a RSD of 3.67%, and storage stability with 92.57% of its initial current response for 37 days. The Au@poly(TTP)/rGO/GCE was employed to estimate DA in injection samples.