Vibrational spectroscopies are pivotal in analytical methods and biomedical diagnostics owing to their singular ability to provide molecular specificity. However, they are intrinsically limited by weak light-matter interactions and vulnerability to intensity fluctuations and spectral interference. Here, we propose a quantum sensing strategy by leveraging hybrid light-matter states under vibrational strong coupling between molecular vibrations and an optical cavity mode. These quantum vibropolaritonic states exhibit characteristic vacuum Rabi splitting, which not only enables manipulation of molecular vibrations but also provides a unique optical transducer. The feasibility of this strategy is established by combining theoretical analysis and numerical simulations. Through fabrication of a microfluidic infrared flow cell, definitive experimental validation of vibropolaritonic sensing is achieved. We believe that this study represents a major advance in harnessing hybrid light-matter states for molecular sensing and offers exciting potential to affect applications in areas including chemical sensing, environmental monitoring, biomedical diagnostics, and bioprocess monitoring.