Diamantina National Park, Nature reserve in Queensland, Australia.

Diamantina National Park covers about 507,000 ha in the Channel Country, from sandstone ranges in the east to the flat plain of the Diamantina River. Between them lie Mitchell grass downs, dune fields and desert in the west. Lake Constance and Hunters Gorge are notable features; average elevation is 139 m.

The reserve was established in 1993 after the Queensland Government acquired the Diamantina Lakes Station property. The park was named after Lady Diamantina Bowen, wife of Queensland's first governor.

Parts of the park lie on traditional Aboriginal lands of the Maiawali and Karuwali, noted for food resources and numerous habitation sites. Groups moved from the sandhills and gibber country in the wet season and returned to permanent water in the dry season.

The park lies about 1,278 km west of Brisbane and 300 km southwest of Winton, reached by unsealed roads, so check road closures and weather before setting out. Two campgrounds serve visitors: Hunters Gorge, about 10 km north of the park administration, and Gum Hole, roughly 11 km west of Hunters Gorge on Duck Creek.

The reserve holds the largest known population of night parrots, a bird species once thought nearly extinct. This discovery in 2016 made the area a critical habitat for one of Australia's rarest birds.