Xanthichthys greenei sp. n. is described from six specimens, 97-154 mm standard length (SL) collected from mesophotic coral ecosystems (90-100 m) at Kiritimati (Christmas Island), Line Islands, part of the Republic of Kiribati in the Central Pacific. Of the six species of Xanthichthys, it is most similar to the Atlantic X. ringens and the Indo-West Pacific X. lineopunctatus, sharing with these species the character of three pigmented cheek grooves. It is distinctive in its low body scale row count (33-35, other Xanthichthys species with 39 or more), small size (maximum SL 154 mm, other species over 225 mm), and color pattern of scattered dark spots sub-dorsally and no other spots or lines on body.