The rapid development of wearable smart garment urgently demands a matchable flexible battery. Nevertheless, the deformability provided by common sandwich batteries is not enough. Fiber-shaped batteries may present an effective strategy to possess omni-directional deformability, yet it often needs a complex assembly and has a large diameter, resulting to a limited overall compatibility/integration with the fabric. In this work, a deformable Ni-Zn fabric battery has been designed by separately sewing thread cathode and anode with snake-shaped footprint onto the existing rib fabric. Attributed to the flexible and durable core-shell thread cathode as well as the snake-shaped sewing footprint, the Ni-Zn fabric battery is flexible and stretchable. It can remain 91.81% capacity with 66% stretching strain. Furthermore, the fabric battery can be integrated into the garment to power wearable microelectronic devices without affecting the appearance or comfort of the garment. The Ni-Zn fabric battery is stretchable, flexible, light, safe, scalable, detachable and simple to assemble, showing a huge potential to be a preferable flexible energy source for the wearable smart garment.