Abstract Piezoelectric nanomaterials are gaining prominence in biomedicine, showing remarkable potential due to their ultrasonic response properties and unique physical and chemical characteristics. However, the core mechanism, especially the interdisciplinary interactions between nanoparticles and cells, is still ambiguous, thus impeding further applications. In this Perspective, the piezo‐bio interaction interface is presented as a key for unlocking interaction mechanisms and regulating cellular behaviors. The brief principles of piezoelectricity are summarized, surface electric field and interface engineering, then analyze the underlying interaction mechanisms at the interface from both physical and chemical perspectives. On these basis, a detailed discussion is conducted on how to manipulate biological processes by regulating crucial biomolecules through piezo‐bio interaction interfaces. Finally, the beneficial outlooks are presented to enlighten the brand‐new applications of piezo‐bio interaction interfaces in both fundamental research and biomedical applications. Hopefully, this Perspective can foster the interdisciplinary integration of materials science, physics, chemistry, and biology, further inspiring the advances of piezoelectric nanomaterials in biomedicine.