Rhodolaena macrocarpa grows as a tree up to tall. The branches are glabrous. Its leaves, also glabrous, are elliptic in shape, dry olive green and measure up to long. The inflorescences have a single flower, uniquely for the genus, on a peduncle measuring up to long. Individual flowers are large with five sepals and five purple-red petals, measuring up to long. The roundfruits are large and woody, measuring up to in diameter, with a fleshy involucre. The fruit is the largest of the genus.