Abstract <p>Based on the coupling effect of piezoelectric, semiconductor, and photonic properties, the fast-growing area of piezotronics and piezo-phototronics has inspired the discovery of fundamental phenomena in a variety of materials, and it has also dramatically advanced the sensor technology that is essential for industrial applications and daily life. This article addresses the fundamental principles, material issues, device architecture, and application of piezotronic and piezo-phototronic sensors. The discovery of flexoelectronics and surface piezotronics has enabled devices to be fabricated from non-piezoelectric materials with centrosymmetric structures. The piezopotential is creatively used to design and manufacture sensors with outstanding sensitivity for mechanical, thermal, chemical, and optical detection. Piezotronics and piezo-phototronics contribute to developing self-powered sensors assisted by energy harvesting with the mechanical–electrical coupling effect. Despite still in their infancy, piezotronic and piezo-phototronic sensors have broad application prospects in smart manufacturing, wearable technology, health monitoring and diagnosis, and artificial intelligence.</p> Graphical abstract <p></p>