Cereblon (CRBN) is a ubiquitin ligase widely harnessed for targeted protein degradation. We report the discovery of a molecular glue that drives CRBN homo-dimerization and subsequent fast, potent, and selective CRBN degradation by the ubiquitin proteasome system. The structure of the complex reveals a unique mechanism whereby two molecular glues assemble into a helix-like structure and drive ternary complex formation by mimicking a protein degron in trans.