This Special Issue of Micromachines, titled "Nanomaterials for Micro/Nanodevices", comprehensively examines the intersection of nanotechnology and micro/nanodevices. This issue is a collection of ten papers that explores the cutting-edge developments and applications of nanomaterials in the fabrication and performance enhancement of micro- and nano-scale devices. As the demand for smaller, faster, and more efficient electronic and mechanical systems grows, nanomaterials play a pivotal role in revolutionizing device engineering. Nanomaterials offer unique electrical, mechanical, and chemical properties that make them ideal for pushing the boundaries of micro/nanodevice performance. By advancing the interface between materials science and nanotechnology, this issue showcases innovative research driving the future of micro-/nano-scale technologies. Additionally, it addresses challenges such as scalability, cost-effective manufacturing, and material-device compatibility. These featured studies provide insights into current limitations that nanomaterials can address through interdisciplinary collaboration, setting the stage for next-generation innovations in electronics, energy harvesting, and biomedical technologies.