Flexible energy storage devices are attracting a great attention nowadays in the rapidly growing area of implantable/wearable electronics. This bloom has generated great demands on flexible wire-shaped supercapacitors (WSC) as power sources in wearable electronic systems that can offer tunable sizes, shapes, and versatile designs. Herein, a flexible WSC is fabricated using MgMn2O4 nanofibers (MMO-NFs) over a flexible carbon yarn substrate via the electrophoretic deposition method in the first report. The binder-free deposition of highly porous and one-dimensionally aligned MMO-NFs over carbon yarn offers excellent ionic/charge transport into the fabricated device. The assembled WSC device at 0.1 mA/cm current rate shows capacitances of 386 mF/cm2 and 45.5 mF/cm. A capacitance retention of 88% for a WSC device after 10,000 cycles indicates its good cyclability. Further, the WSC exhibits good flexibility, retaining 94% of capacitance at 0.5 mA/cm after 2000 bending cycles. Furthermore, the flexible WSC device shows power and energy density of 744 μW/cm and 14.2 μWh/cm, respectively. Additionally, WSC devices demonstrate their practical energy storage capabilities in a video that shows three similar devices being knitted into a wearable glove and glowing a red light-emitting diode (LED) for more than five minutes in various bending positions.