Lithium rubidium borate (LiRbB4O7) single crystal has been grown by the Czochralski method. Crystalline perfection and optical homogeneity of the grown LiRbB4O7 crystal are analyzed by high resolution X-ray diffraction and birefringence interferometric technique, respectively. Third order nonlinear optical parameters of LiRbB4O7 crystal are determined by Z-scan experimental technique. The nonlinear refractive index (n2) and third-order nonlinear optical susceptibility (χ3) are estimated to be −4.935 × 10−11 cm2/W and 2.719 × 10−7 esu, respectively. The measured (n2) value reveals the self-focusing nature of LiRbB4O7 crystal.