A new species of the phyline plant bug genus Rubrocuneocoris Schuh (Hetereroptera: Miridae) is described from Hawaii. Although known only from the Oahu and Hawaii in the Hawaiian Islands, it is considered an adventive species originating from elsewhere in eastern Asia or the Indo-Pacific Region. A diagnosis, description, habitus images, and illustrations of male genitalia are provided to help distinguish this new species from the other 13 previously known species of the genus.