Core-shell titanium carbide/carbon (TiC@C) and titanium carbide/nitrogen-doped carbon (TiC@CNx) quasi-aligned nanofiber arrays (NFAs) are fabricated on biomedical Ti-6Al-4V by a simple thermal chemical process in the presence of benzene and pyridine at 800 °C, respectively. The morphology, structure, and composition of the TiC@C and TiC@CNx NFAs are characterized by X-ray diffraction, electron microscopy, energy-dispersive X-ray spectrometry, and Raman scattering spectroscopy. The TiC@C and TiC@CNx nanofibers consisting of highly conducting single-crystalline TiC cores and carbon shells or N-doped carbon shells have a large amount of defects and N doping endows the TiC@CNx NFAs with excellent electrochemical properties. The TiC@CNx NFAs electrode exhibits fast heterogeneous electron transfer (HET) kinetics in the Fe(CN)63−/4− redox couple showing an ideal peak-to-peak potential separation (59 mV) at a high scan rate of 7000 mV s−1. As a result, the TiC@CNx NFAs electrode has high activity in the simultaneous detection of dopamine (DA), ascorbic acid (AA), uric acid (UA), and serotonin (5-hydroxytryptamine, 5-HT) as well as high sensitivity and selectivity in the determination of DA in the presence of UA, AA, and 5-HT. The linear range for the determination of DA is 0.5–180 μM and detection limit is 8 nM (S/N = 3).