This work discuses indium tin oxide (ITO) coated optical fiber lossy-mode resonance (LMR) sensor working in an electrochemical setup for monitoring of protein binding to the sensor’s surface. The binding mechanism has been observed simultaneously in optical and electrochemical domain. The combined measurement was enabled by the electrically conductive ITO overlay. In the experiment, biotin molecules have been used to test the collective optical and electrochemical setup and to illustrate the binding effect. It has been shown that the effect is observed in the investigated domains at applied potential, and the qualitative comparison shows high resemblance of the outcome.