Vigna owahuensis is a rare species of flowering plant in the legume family known by the common name Oahu cowpea. It is endemic to Hawaii, where it is known from seven small populations on the islands of Hawaii, Molokai, Lanai, and Kahoolawe. Though it was described from a specimen collected on Oahu it is now extirpated from that island. It was also known from Niihau, Maui, and Kauai in the past. It is threatened by habitat destruction and degradation.