Zn metal batteries have garnered considerable scientific and technological interests. However, the widespread commercial application of these batteries is impeded by the uncontrollable dendrite growth and consequent severe side effects. Herein, a functionalized separator is prepared by spraying polyaniline‐modified graphene oxide (denoted as NPGO)/polyvinylidene difluoride solution directly on one side of a common separator of glass fibers (GFs). The reversible transition between protonated and deprotonated states of quinolone imide on NPGO nanosheets can facilitate the rapid desolvation and transfer of Zn2+. Therefore, the spatial electric field as well as the Zn2+ flux is effectively homogenized due to the ion‐sieving effect of NPGO nanosheets that are oriented toward Zn anode. This engineering design of the NPGO@GFs separator harvests excellent rate and cycling performance (over 3000 cycles at 20 mA cm−2) for Zn metal symmetric batteries. Meanwhile, it provides an impressive commercial prospect (500 cycles with a capacity retention of 91.6% under 2000 mA g−1) for MnO2||Zn full batteries. Such a strategy can be generalized as a common way to protect metal anodes (Na, Zn, and K) in rechargeable batteries, which is highly cost‐effective and scalable. [ABSTRACT FROM AUTHOR]