Xanthophyllum rectum is a tree in the family Polygalaceae. The specific epithet ' is from the Latin meaning 'upright', referring to the inflorescences.
Xanthophyllum rectum grows up to tall with a trunk diameter of up to . The smooth bark is pale grey. The dark brown fruits are round and measure up to in diameter.
Xanthophyllum rectum is endemic to Borneo and confined to Sarawak. Its habitats include kerangas and dipterocarp forests.