AbstractDiamond has numerous outstanding properties in mechanics, physics, chemistry, electronics, thermodynamics, and spintronics for either classic micro/nanoelectromechanical systems (MEMS/NEMS) devices or hybrid quantum MEMS/NEMS systems. The extremely high mechanical strength and the ultra‐wide bandgap energy enable the development of mechanically and thermally robust MEMS/NEMS sensors and switches, while the long coherence time of spin defects center enables the reading out through optical methods, precise quantum sensing, and quantum information processing. In this paper, the development of diamond‐based MEMS/NEMS from the viewpoints of classic devices to quantum systems are reviewed. The fabrication process and the classic applications of diamond MEMS/NEMS devices are first described, including those from micro‐crystalline, nano‐crystalline/ultranano‐crystalline, and single‐crystalline diamonds. Then, the physical properties of nitrogen‐vacancy defect center, as well as the application referred to the hybrid system composed of MEMS structures and nitrogen‐vacancy centers embedded, strain–spin interaction, and diamond‐based optomechanics are introduced. Finally, a conclusion and outlook are presented. It is expected that diamond MEMS/NEMS is not only an ideal platform for high‐performance and high‐reliability advanced classic MEMS devices but also for quantum sensing, information, and exploring the fundamentals of quantum mechanics.