In the ongoing battle against antimicrobial resistance (AMR), niobium carbide (NbC) submicron particles have emerged as a potential ally, thanks to their unique physicochemical properties boosted from a high surface-to-volume ratio. Synthesized through an innovative molten salt technique, these particles demonstrate promising photoactivity for photothermal therapy (PTT), a promising alternative to traditional antimicrobial strategies. This study elucidates the characterization and potential biomedical applications of NbC submicron particles, focusing on their size, dispersion, and photoactivity profiles. Our results indicate that the meticulous synthesis process produced NbC particles with average sizes of 1,7 µm in a narrow particle size distribution, which is advantageous for maintaining the high surface area required for effective PTT. Small and homogeneous dispersion of particle sizes is crucial for ensuring consistent bioactivity and minimizing potential cytotoxicity. Spectroscopic analysis demonstrated that upon excitation with an 800 nm laser, the NbC submicron particles exhibit a significant absorbance with an exponential decay over time, indicating their capability to maintain a prolonged photoactive state. This property is critical in PTT, where sustained heat generation can induce bacterial cell death. The characteristic time constant from the absorbance data suggests that these particles can offer a sustained antimicrobial effect upon NIR light exposure, a novel approach to tackle AMR. In conclusion, the NbC particles’ potential for inducing photothermal damage opens a new avenue for antimicrobial therapy. Their low toxicity profile, combined with high antimicrobial efficacy, could significantly impact the management of infections, especially those resistant to existing treatments. Future work will focus on in vivo applications, aiming to translate these promising in vitro results into clinical reality, thereby contributing to the advancement of nanotechnology in medicine.