This book presents an innovative methodology to fabricate nanostructured piezoelectric composite fibers with wearable technologies application as an energy generator and/or sensors. It reports on methods of piezoelectric fiber formation and development of novel textile structures (weave, knit, braid, coil) with embedded electrodes. The flexibility and small diameter of the final fiber make it possible to use them in garment without affecting structure of comfort. The performance of the fiber generators was evaluated through different applications such as air and water sensor, health and movement monitoring, and energy generator. The book targets a wide readership including materials scientists, electrical engineering, soft robotics, Internet of things, electronic textiles, and wearable technology.