A top-down strategy using acid etching followed by water soaking is utilized to in situ synthesize autologous NiFe LDH nanosheets on NiFe foam without other metal ions, oxidizing agents or heating steps. The NiFe foam serves as both the metal source and substrate, and the obtained nanosheets are firmly anchored on the foam. The obtained ultrathin nanosheet arrays could greatly increase the electrocatalytic active sites. This factor together with the synergistic effect between Fe and Ni simultaneously leads to an enhanced catalytic effect for water splitting and urea oxidation. This strategy could be scaled up to pave a viable way for low-cost fabrication of highly efficient electrodes for electrocatalysis.