We report the growth and characterization of single-crystalline, crack-free, epitaxial (0001) ZnO films on (111) Si substrates using intervening epitaxial Lu2O3 buffer layers. The epitaxial orientation relationships are (0001)ZnO||(111)Lu2O3||(111)Si and ZnO||Lu2O3||Si. X-ray diffraction and transmission electron microscopy reveal that the ZnO films have high structural quality and an atomically sharp ZnO/Lu2O3 interface. Temperature-dependent photoluminescence measurements show optical properties comparable to ZnO single crystals. The films have a resistivity of 0.31 Ω cm, an electron concentration of 2.5×1017 cm-3, and a mobility of 80 cm2/V∙s at room temperature. The epitaxial growth of ZnO on Si represents a significant step toward the integration of ZnO-based multifunctional devices with Si electronics.