Lithium metal is the only anode material that can enable the Li−O2 battery to realize its high theoretical energy density (≈3500 Wh kg−1). However, the inherent uncontrolled dendrite growth and serious corrosion limitations of lithium metal anodes make it experience fast degradation and impede the practical application of Li−O2 batteries. Herein, a multifunctional complementary LiF/F‐doped carbon gradient protection layer on a lithium metal anode by one‐step in situ reaction of molten Li with poly(tetrafluoroethylene) (PTFE) is developed. The abundant strong polar C‐F bonds in the upper carbon can not only act as Li+ capture site to pre‐uniform Li+ flux but also regulate the electron configuration of LiF to make Li+ quasi‐spontaneously diffuse from carbon to LiF surface, avoiding the strong Li+‐adhesion‐induced Li aggregation. For LiF, it can behave as fast Li+ conductor and homogenize the nucleation sites on lithium, as well as ensure firm connection with lithium. As a result, this well‐designed protection layer endows the Li metal anode with dendrite‐free plating/stripping and anticorrosion behavior both in ether‐based and carbonate ester‐based electrolytes. Even applied protected Li anodes in Li−O2 batteries, its superiority can still be maintained, making the cell achieve stable cycling performance (180 cycles). A gradient LiF/F‐doped carbon protection layer with synergistic functions of homogenizing Li+ flux, fast Li+ diffusion ability, and low Li+ diffusion barrier is prepared by a one‐step in situ reaction to solve the challenges relating to unstable lithium anode in Li–O2 batteries, and, as a result, significantly boost the cycling stability of the Li–O2 batteries.