Carboiodanation of arynes with organo-benziodoxoles (BXs) furnishes aryl-BXs (ArBXs) bearing ortho-alkynyl, alkenyl, or aryl groups, which serve as versatile aromatic building blocks for downstream π-extension through the aryl–iodine(III) bond. Although synthetically valuable, these primary carboiodanation products rarely participate in a second aryne addition due to insufficient nucleophilicity. Here we show that judicious pairing of organo-BXs and arynes enables electronic activation of the initial ArBX product, rendering it competent for a second carboiodanation to afford biaryl-BX derivatives. This unique reactivity arises from a BX-specific arenium/iodate four-membered cyclic intermediate, in which the positive charge is efficiently delocalized by mesomeric effects provided by substituents transferred from β-alkoxyvinyl-BXs (VBXs) and ethynyl-BXs (EBXs), as well as the electron-rich aryl framework formed upon initial aryne incorporation. The resulting biaryl-BX scaffolds provide concise access to densely functionalized oligoarylenes and polycyclic aromatic frameworks.