We introduce a photoswitchable O6-benzylguanine derivative and demonstrate its use for super-resolution microscopy of SNAP-tagged proteins based on single fluorophore localization. Stochastic Optical Reconstruction Microscopy (STORM) reveals SNAP-tagged microtubule structures with ~25 nm resolution. The described probe in combination with the versatile SNAP-tag labeling opens new possibilities for imaging biological structures at the nanoscale.