Carbon nanotubes (CNTs) have shown their potential for broad applications in field effect transistor, field emission, interconnects, energy storage, biomedicine, and many others, due to their excellent electrical, thermal, and mechanical properties. One requirement for many of these applications is to assemble CNTs into designated devices. As a promising nanomanipulation method, dielectrophoresis (DEP) has been widely applied to assemble CNTs in the fabrication of CNT-based nanodevices. This paper presents a brief review of the progress in CNT-based nanosensors and the application of DEP in device making. These sensors focus on the sensing of gases, temperature, bioparticles, light, pressure, stress, and strain.