Achieving direct electron transfer between a biomolecule and modified electrodes is paramount for fabricating advanced biosensor devices. In this report, 1-dimensional (1D) MoO3 nanowires (NWs) were synthesized in a systematic growth evolution study. These MoO3 NWs, with the glassy carbon electrodes (GCEs), were further used as a mediatorless biosensor electrode for the detection of norepinephrine (NE) by cyclic voltammetry and chronoamperometry techniques. The MoO3 NWs/GCE had a magnificent response time of 2 s in the electrochemical detection of NE, with a detection limit of 0.11 mM. This excellent bio-electrochemical performance is attributed to its high catalytic activity and 1D microstructure, providing a path for electron transport and increasing their sensitivity. The MoO3 NWs/GCE also had a promising diffusion constant (D) value of 3.34 x 10(-5)cm(2)/s and a heterogeneous rate constant (k) of 8.03 x 10(-4) cm/s. The modified electrode possessed high stability, reproducibility, and selectivity. (C) 2017 Elsevier Ltd. All rights reserved.