To address the challenge of balancing stretchability and conductivity in wearable strain sensors, a conductive fiber termed MXene-TPU (MTF) has been developed. This fiber is based on thermoplastic polyurethane (TPU) as the substrate, with Ti3C2Tx MXene nanosheets prepared through an in-situ hydrofluoric acid etching process serving as the conductive material. The MXene-TPU conductive fiber is fabricated by wet spinning. Using SEM and EDS characterization, combined with experimental techniques such as electromechanical stretching/compression, materials mechanics, and human motion monitoring, we investigated the influence of MXene loading on the structure, morphology, mechanical properties, and conductivity of MTF. Additionally, we explored the sensing performance under different tensile strain conditions. The results demonstrate that the establishment of a MXene conductive network within TPU imparts a high gauge factor to the MXene-TPU conductive fiber (MTF), reaching 2930 at 120% strain. The incorporation of MXene enhances the thermal stability of the MXene-TPU conductive fiber (MTF), increasing its thermal decomposition temperature from 360°C, as observed in polyurethane fiber (TF), to 400°C. MXene forms continuous conductive pathways on both the surface and within the fiber, imparting good conductivity to the fiber (electrical conductivity of 141.54 S/m). MXene also enhances the modulus of the MXene-TPU conductive fiber (MTF). For MTF2 with a MXene loading of 21.74%, the stress at 50% strain (σ50) is 1.3 times higher than that of TF, indicating a certain level of tensile strain recovery. MTF2 corresponds to different human joint movements by expressing varying rates of resistance changes, making it suitable for human motion monitoring.