Heteroepitaxial growth of well-aligned ZnO nanorod arrays on GaAs (111) substrates was achieved through electrochemical deposition at low temperature without any buffer layers for the first time. Structural analysis demonstrated the epitaxial orientation relationship of ZnO(0001)//GaAs(111). The rod density was dependent on the applied current density. These ZnO nanorods had high crystalline quality andexhibited strong UV near-edge photoluminescence with a 106 meV full-width at half-maximum and very weak deep level emission. Furthermore, the patterned growth was facially implemented by using surface masks on cathode substrates. These results are envisaged to advance the development of ZnO nanorod-based heterojunctions and their applications in optoelectronics.