Wearable Internet of Things devices require innovatively designed electromagnetic materials and energy harvesting technology that is lightweight and able to withstand vigorous exercise and impact. In this study, magnetostrictive wire/polymer composites are developed for the first time by embedding Fe–Co wires in an epoxy matrix, and their inverse magnetostrictive characteristics are studied. The output voltage of this novel composite due to compression dramatically increases with increasing stress-rate. Synthesis of the Fe–Co wire-based composite may induce tensile prestress (rather than compressive prestress) during curing, leading to an extraordinary inverse magnetostriction enhancement. This work opens the door for development of lightweight, robust, and efficient energy harvesting devices.