Isoindolones constitute a dominant structural class in synthetic and medicinal chemistry. In this research, an electrochemical reaction involving 2-alkynylbenzamides, inorganic sulfites, and alcohols was first established to provide sulfonyl ester-substituted 3-hydroxyisoindolinone derivatives in moderate to good yields with excellent functional group tolerance. When bulky aryl-substituted 2-alkynylbenzamides are utilized as substrates, sulfonyl ester-substituted 3-alkylideneisoindolinones can be selectively generated with good chemoselectivity. Alkoxysulfonyl radicals derived from the anodic oxidation of inorganic sulfite with alcohols are involved in this transformation.