Thermoset polymers are the most common matrix used for manufacturing fiber-reinforced polymer composites, with their exceptional properties leading to their usage in highly demanding fields such as aerospace. Monitoring such materials for structural deformation is key when it comes to maintaining their continual usage and avoiding catastrophic failure. Here, we explore how single-walled carbon nanotube (SWCNTs) nano–macro arrangements can be used to monitor composites under tensile loading without causing a loss in host material properties. Sensors of various thicknesses (23, 37, and 53 nm) were investigated to determine optimized monitoring parameters: electrode materials, configuration, and embedding within or surface application. Tensile loading was conducted with a crosshead speed of 1mm/min, and strain measurements were obtained using digital image correlation. It was found that thinner sensors provided higher sensitivity to mechanical deformation and load, and that embedded sensors outperform surface-applied ones (gauge factors between 23 and 86 and 4 and 10, respectively). All sensors were shown to accurately measure strain, and were shown to self-adjust to elastic and plastic deformation regimes during mechanical loading. We show that monitoring of the mechanical deformation and loading of popular industrial polymers and composites can be accurately conducted using optimized SWCNT structures, and that their application causes no degradation in thermoset polymer material performance.