Developing stable and advanced aqueous Ni-Zn battery for meeting the power-source demands of wearable electronics are highly desirable. Herein, a facile and effective approach is proposed to activate commercial Ni foil to form highly active Ni(OH)2 layer as robust cathode for Ni//Zn battery. In comparison to the pristine Ni foil, the capacity of the activated Ni foils is greatly enhanced, yielding a remarkable discharge capacity of 0.57 mAh cm−3 with excellent rate and cycling performances. When directly using the activated Ni foils as cathode, a high-performance Ni//Zn battery with a maximum volumetric energy density of 2.89 mWh cm−3 is achieved. More improtantly, this as-fabricated Ni//Zn battery also owns outstanding cyclic stability, without any capacity decay after 5000 cycles under various current densities.