The first total synthesis of (+)-vibsanin A, an 11-membered vibsane diterpenoid, was achieved, unambiguously establishing its relative and absolute stereochemistry. Highlights of the synthesis include the stereoselective formation of an all-carbon quaternary stereocenter by a zinc-mediated Barbier-type allylation in an aqueous medium, and the efficient construction of an 11-membered ring skeleton by a combination of an intramolecular Nozaki-Hiyama-Kishi (NHK) reaction and a Mitsunobu reaction.