Precision actuation is a foundational technology in high-end equipment domains, where stroke, velocity, and accuracy are critical for processing and/or detection quality, precision in spacecraft flight trajectories, and accuracy in weapon system strikes. Piezoelectric actuators (PEAs), known for their nanometer-level precision, flexible stroke, resistance to electromagnetic interference, and scalable structure, have been widely adopted across various fields. Therefore, this study focuses on extreme scenarios involving ultra-high precision (micrometer and beyond), minuscule scales, and highly complex operational conditions. It provides a comprehensive overview of the types, working principles, advantages, and disadvantages of PEAs, along with their potential applications in piezo-actuated smart mechatronic systems (PSMSs). To address the demands of extreme scenarios in high-end equipment fields, we have identified five representative application areas: positioning and alignment, biomedical device configuration, advanced manufacturing and processing, vibration mitigation, micro robot system. Each area is further divided into specific subcategories, where we explore the underlying relationships, mechanisms, representative schemes, and characteristics. Finally, we discuss the challenges and future development trends related to PEAs and PSMSs. This work aims to showcase the latest advancements in the application of PEAs and provide valuable guidance for researchers in this field.