The transition metal-catalyzed Catellani reaction of aryl halides has drawn significant attentions as an efficient and practical tool for the synthesis of substituted arenes. We describe herein the palladium-catalyzed, norbornene (NBE)-mediated synthesis of polysubstituted arenes from aromatic acids via decarbonylative Catellani reaction. A variety of alkenyl, alkyl, aryl and sulfur moieties could be conveniently introduced into the ipso-positions of aromatic thioesters. By merging carboxyl-directed C−H functionalization and the classical Catellani reactions, our protocol allowed the construction of 1,2,3-trisubstituted and 1,2,3,4-tetrasubstituted arenes from simple aromatic acids. Furthermore, the late-stage functionalization of a series of drug molecules highlights the potential utility of the reaction.