The chirality-induced spin selectivity (CISS) has been found in the antiferromagnetic and paramagnetic chiral inorganic materials with unpaired electrons, while rarely reported in the spin-paired diamagnetic inorganic materials with spin-pairing energy. Here, we report the CISS in the spin-paired diamagnetic BiOBr endowed with three levels of chiral mesostructures. Chiral mesostructured BiOBr films (CMBFs) were fabricated through a sugar alcohol-induced hydrothermal route. The antipodal CMBFs exhibited chirality-dependent, magnetic field-independent magnetic circular dichroism (MCD) signals, which indicates the existence of spin selectivity. The spin selectivity of CMBFs was speculated to be the result of the competing effect between the externally applied magnetic field and the effective magnetic field arisen from the spin electron motions in chiral potential. The chirality-induced effective magnetic field acts on the magnetic moment of electrons, potentially overcoming the spin-pairing energy and producing opposite energy changes for spin-down and spin-up electrons.