With progressions in nanotechnology allowing for the precise structuring of materials at the nanoscale, there is a growing opportunity to develop innovative material systems and active response capabilities. The inherent coupling between electrical properties and mechanical deformation in carbon nanotubes makes them ideal candidates for future multifunctional materials that integrate adaptive and sensory functions. To design these advanced material systems for sensing and actuation, a fundamental understanding of their structure-property relationships is essential. This chapter reviews recent progress in nanotube and nanotube-based composite sensors and actuatorsSensors and actuators, with a particular focus on their electromechanical behavior. It begins by introducing the fundamentals of carbon nanotubeCarbon Nanotube (CNT) electromechanical propertiesElectromechanical properties and their application in nanoscale sensor and actuator systems. Next, research on the electrical percolation behavior of carbon nanotube-based composites is examined. Finally, the development of these compositesComposites and their potential for use as macroscopic actuators and sensors is explored.