The roles of Li2O and B2O3 and heat-treatment condition on crystallization behavior and flowability of leucite–fluoroapatite-based glass-ceramic glazes were investigated. The thermal expansion coefficient, mechanical, and chemical properties of the optimum specimen were determined. Glaze firing was performed in the 650–1100°C interval, in one and two step processes. Based on the results, B2O3 was more effective than Li2O in point of flowability view. Also, the microstructures varied with the adopted firing process, so that the two-step heat-treated sample showed superior mechanical properties than the one-step heat-treated specimens.