We report the realization of defect-free InAsSb nanowire (NW) arrays on Si substrates by selective-area metal-organic chemical vapor deposition. We studied the effects of growth temperature and the morphology of patterned Si/SiO2 substrates on the formation of InAsSb NW arrays, and found that both the morphology and the yield of the NW arrays were sensitive to the growth conditions. By optimizing the growth conditions, we achieved high-quality InAsSb NW arrays, which exhibited a pure zinc-blende crystal structure without any defects. In addition, based on the as-grown NWs, we fabricated back-gated field effect transistors devices that showed an electron mobility of 2000 cm2 V-1 s-1 at room temperature.