Titanium nitride (TiN), as an excellent alternative plasmonic supporting material compared to gold and silver, exhibits tunable plasmonic properties in the visible and near-infrared spectra. However, label-free surface plasmon resonance biosensing with TiN is seldom reported due to lack of proper surface functionalization protocols. Herein, this study reports biotinylated antibody-functionalized TiN (BAF-TiN) for high-performance label-free biosensing applications. The BAF-TiN biosensor can quantitatively detect exosomes of 30-200 nm extracellular vesicles, isolated from a human glioma cell line. The limit of detection for an exosomal membrane protein with the BAF-TiN biosensor is found to be 4.29 × 10 −3 µg mL −1 for CD63, an exosome marker, and 2.75 × 10 −3 µg mL −1 for epidermal growth factor receptor variant-III, a glioma specific mutant protein, respectively. In conclusion, combining the biocompatibility, high stability, and excellent label-free sensing performance of TiN, the BAF-TiN biosensor could have great potential for the detection of cancer biomarkers, including exosomal surface proteins.