A novel metallo-organically templated pentaborate with layered framework, [Cd(TETA)(C2H3O2)][B5O6(OH)4] (1) (TETA = triethylenetramine), was synthesized under mild solvothermal conditions. The structure was determined by single-crystal X-ray diffraction and further characterized by FT-IR spectroscopy, elemental analysis, thermogravimetric analysis, and photoluminescence spectroscopy. The structure consists of an isolated polyborate anion [B5O6(OH)4]– and the cadmium complex cation of [Cd(TETA)(C2H3O2)]+, which contains both organic amine and organic acid ligands. The [B5O6(OH)4]– units are connected together by hydrogen bonds, and a 2D sheet-like framework with rectangle-like 12-membered boron rings are formed. The [Cd(TETA)(C2H3O2)]+ complex cations are located in the free space between the layers and connect the adjacent borate layers through hydrogen bonds to form a three-dimensional supramolecular network. The luminescent properties of the compound were studied for the first time in the series of metallo-organically-templated pentaborates, and a blue luminescence occurs with an emission maximum at 468 nm upon excitation at 397 nm.