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. Graphical abstract