TPU nanofiber membranes were firstly prepared by the electrospinning technique, and Ti3C2Tx-MXene/TPU nanofiber yarns were fabricated by the “Biscrolling” method. The obtained composite nanofiber yarns were characterized by SEM, electrical resistance test, sensing performance test and other techniques. The results showed that the tensile strength of the composite yarn was firstly increased and then decreased with the loading of MXene, and the breaking strain was more than 459%, demonstrating good elasticity. In addition, continuous and conductive MXene film can be constructed on the inner and outside the yarn, rendering the composite yarn with low electrical resistance (76 Ω/cm). The strain sensing performance of the composite yarns were also investigated, and the results revealed that MXene/TPU nanofiber yarns had the gauge factor and linearity of 477.86 and 0.995, respectively, which were higher than that of most of yarn strain sensors. In addition, the MXene/TPU nanofiber yarns can be used to monitor various motion states of human body.