TiO 2 -based two-dimensional nanosheet composite materials are promising photocatalysts for water splitting. The mesoporous structure possesses a high surface-to-volume ratio with more active sites. It is fantastic for photocatalysts to integrate the advantages of a porous structure into two-dimensional materials. The calcined ultrathin layered double hydroxides (LDHs) are porous metal oxide nanosheets, which are considered ideal templates to construct photocatalysts. In this work, we report the design and fabrication of amorphous aluminum oxide-supported anatase TiO 2 /spinel Co 3 O 4 (TiO 2 /Co 3 O 4 ) mesoporous nanosheets by calcinating ultrathin TiO 2 /CoAl-LDH precursors. The built-in electric field in the TiO 2 /Co 3 O 4 interface facilitates the charge transfer, and Co 3 O 4 acts as a cocatalyst to further enhance the oxygen evolution reaction activity. Consequently, the TiO 2 /Co 3 O 4 photocatalyst exhibits excellent photocatalytic performances for the evolution of O 2 and H 2 . This strategy for preparing mesoporous nanosheet photocatalysts is expected to extend to the other metal oxide semiconductor systems.