Xanthostemon formosus is a species of tree in the myrtle family Myrtaceae that is endemic to north-eastern Queensland, Australia.

[1] The species may reach a height of 18 m with a stem diameter of 30 cm.

The crowded leaves are about 12–22 cm long by 2–4.5 cm wide, forming whorls on the twigs.

[2][1] Endemic to the wet tropics of north-eastern Queensland, the species is restricted to a few streams between the Daintree River and Cape Tribulation, with an altitudinal range from close to sea level to 100 m. It grows as a rheophyte along rocky or boulder-strewn streams flowing through rainforest.

[1] This Myrtaceae article is a stub.