Rapid in situ monitoring of hydrogen peroxide (H2O2) released from living cells is of great significance for the early diagnosis, case analysis, and treatment of tumors. In this work, a sensitive MIL-47(V)-OH monitoring sensor was designed by adjusting the ligand of MIL-47(V) to realize the rapid in-situ detection of H2O2 released from living cells with high selectivity. The working potential of the as-designed sensor was optimized, and the electrochemical reaction products of H2O2 under different working potentials were analyzed by electron paramagnetic resonance (EPR). Even without an applied voltage, MIL-47(V)-OH can convert H2O2 into ·O2−, which validates its ability to inhibit tumor cells. Hence, MIL-47(V)-OH is a promising material for H2O2 detection, tumor cell inhibition, and thus, application in biological diagnoses and oncology therapy.