We report a ligand-controlled palladium-catalyzed carbonylation of thianthrenium salts employing HCOOH or DCOOD as a CO source. This divergent method enables the synthesis of aromatic aldehydes, deuterated aromatic aldehydes, aromatic carboxylic acids, alkenyl carboxylic acids, and aromatic esters in moderate to good yields. The reaction demonstrates excellent functional group tolerance, scalability, and utility in the synthesis of medicinally relevant molecules and late-stage functionalization of bio-relevant compounds.