Numerous studies have been conducted on the development of plasmonic strain sensors that can be used for real-time detection and monitoring of human body motions. However, achieving high sensitivity, analytical quantification, and ease of manufacturing remains a major challenge. In this study, gold nanochains (AuNCs) were embedded into the thermoplastic polyurethane (TPU) nanofiber to fabricate a sensitive and stretchable plasmonic strain sensor. When strain tension is applied to these nanofibers, the change in the interparticle distance causes a plasmonic shift, which induces a color change. UV-VIS spectroscopy, scanning electron microscopy, and transmission electron microscopy were used to characterize the developed strain sensors. Results demonstrate a significant color change at 250% tensile strength with sensor cyclic strain durability over 1000 cycles of repeated testing. Our developed technology is expected to contribute significantly to the motion detection applications.