Directional growth of ultralong nanowires (NWs) is significant for practical application of large-scale optoelectronic integration. Here, we demonstrate the controlled growth of in-plane directional perovskite CsPbBr3 NW-s, induced by graphoepitaidal effect on annealed M-plane sapphire substrates. The wires have a diameter of several hundred nanometers, with lengths up to several millimeters. Microstructure characterization shows that CsPbBr3 NWs are high-quality single crystals, with smooth surfaces and well-defined cross section. The NWs have very strong band-edge photoluminescence (PL) with a long PL lifetime of similar to 25 ns and can realize high quality optical waveguides. Photodetectors constructed on these individual NWs exhibit excellent photoresponse with an ultrahigh responsivity of 4400 A/W and a very fast response speed of 252 mu s. This work presents an important step toward scalable growth of high-quality perovskite NWs, which will provide promising opportunities in constructing integrated nanophotonic and optoelectronic systems.