Eu3+-doped cesium barium borate glass with the composition of Cs(2)O2BaO3B(2)O(3) was prepared by the conventional melt quenching method. The glass-ceramic sample was obtained from the re-crystallization of the as-made glass to change the amorphous glass into a crystalline host. This reduces the Eu3+ in glass to Eu2+ ions resulting in a yellow-emitting phosphor of Eu2+-activated CsBaB3O6. The samples were investigated by the XRD patterns and SEM micrograph, the optical absorption, the photoluminescence spectra, and decay curves. The as-made glass has only Eu3+ centers. Under the excitation of blue or near-UV light, Eu2+-doped CsBaB3O6 presents yellow-emitting color from the allowed inter-configurational 4f-5d transition in the Eu2+ ions. The maximum absolute luminescence quantum efficiencies of Eu2+-doped CsBaB3O6 phosphor was measured to be 47% excited at 430nm light at 300K. By taking into account the efficient excitation in blue wavelength region, this new phosphor could be a potential yellow-emitting phosphor for an application in white light-emitting diodes fabricated with blue chips.