B2O3-added Li(1.5)Al(0.5)Ge(1.5)(PO4)3 (LAGP) glass ceramics showing a room temperature ionic conductivity of 0.67 mS cm(-1) have been synthesized by using a melt-quenching method. The prepared glass ceramics are observed to be stable in tetraethylene glycol dimethyl ether containing lithium bis(trifluoromethane) sulfonamide. The augmented conductivity of the B2O3-added LAGP glass ceramic has improved the plateau potential during discharge. Furthermore, the B2O3-added LAGP glass ceramics are successfully employed as a solid electrolyte in a Li-O2 battery to obtain a stable cycling lifetime of up to 15 cycles with the limited capacity protocol.