In this study, a hybrid (soft and strong) coaxial structured fiber sensor that has high load carrying capacity and high sensing performance for measuring mechanical strain is prepared by using a dry-jet wet spinning system and simple dip-coating method. The strong core of the fiber sensor is made of ultrahigh molecular weight polyethylene that has highly oriented molecular structure due to a hot-stretching process to increase the tensile strength. The soft sheath of the fiber sensor is an electrically conductive layer composed of a multilayer structure with varying concentrations of multiwalled carbon nanotubes and polyurethane layers to enhance the sensing performance. A scanning electron microscope is used to investigate the surface morphology of the fiber sensors. Single filament tensile tests are performed to measure the mechanical properties of the fiber sensors. The signal-to-noise ratio, strain sensitivity, repeatability, and degree of hysteresis of the fiber sensors are measured during static and dynamic tensile tests to determine the sensing performance. Experimental results confirm that the hybrid structured fiber sensor shows significantly enhanced mechanical properties due to the control of the hot-stretching process and significantly enhances sensing performances due to the control of the structural configuration of the conductive layers.