Spins in solids are cornerstone elements of quantum spintronics(1). Leading contenders such as defects in diamond(2-5) or individual phosphorus dopants in silicon(6) have shown spectacular progress, but either lack established nanotechnology or an efficient spin/photon interface. Silicon carbide (SiC) combines the strength of both systems(5):it has a large bandgap with deep defects(7-9) and benefits from mature fabrication techniques(10-12). Here, we report the characterization of photoluminescence and optical spin polarization from single silicon vacancies in SiC, and demonstrate that single spins can be addressed at room temperature. We show coherent control of a single defect spin and find long spin coherence times under ambient conditions. Our study provides evidence that SiC is a promising system for atomic-scale spintronics and quantum technology.