Engelhardia mersingensis is a tree in the family Juglandaceae. It is named for Mount Mersing in Borneo.
Engelhardia mersingensis grows up to tall, with a trunk diameter of up to . It has tall buttresses. The bark is brown to orange. The papery leaves are obovate to elliptic and measure up to long. The fruits are winged.
Engelhardia mersingensis is endemic to Borneo. Its habitat is mixed dipterocarp to submontane forests, at elevations of .