In this study, crystal orientation dependent machinability was investigated in machining of 8 mol% monocrystalline cubic yttria stabilized zirconia (YSZ). The machinability transition from ductile to brittle cutting regime was observed and investigated. Machining characteristics and crack morphologies showed two-fold symmetry following cubic crystal form of YSZ. Then, the stress at the transition point was estimated from the critical stress intensity factor and geometric relationship between cutting directions and corresponding crystal planes. The trend of estimated values showed a good agreement with that of measured values from the experiment. By correlating the stress intensity factor and material’s crystallographic information, the ductile-brittle transition could be predicted in terms of cutting directions. It is anticipated that this research can contribute to understanding and modeling the material behavior of hard brittle ceramics in machining.