The Halmahera rain forests is a tropical moist forest ecoregion in Indonesia. The ecoregion includes the island of Halmahera and neighboring islands, including Bacan, Morotai, the Obi Islands, Ternate, Tidore, Gebe, and many smaller islands.

Halmahera is the largest island in the ecoregion, with an area of 17,780 km². The islands are mountainous, and portions are volcanic in origin. Several volcanoes are still active, including Mount Gamkonora (1,560 m) the highest peak on Halmahera.

The islands that make up the ecoregion are part of Wallacea, a group of islands that are part of the Australasian realm, but were never joined to either the Australian or Asian continents. The islands of Wallacea are home to a mix of plants and animals from both terrestrial realms, and have many unique species that evolved in isolation. The eastern boundary of the ecoregion follows Lydekker's Line, which demarcates the islands of Wallacea from the islands on the Australia-New Guinea continental shelf which were joined during the ice ages when sea levels were lower.

The ecoregion has a tropical rain forest climate.

The main plant communities tropical lowland evergreen and semi-evergreen rain forest.

Syzygium aromaticum is native to the ecoregion, and its aromatic flower buds are the source of the spice clove. Myristica fragrans, another native, is the source of nutmeg and mace, which are derived from its seeds. Both trees are widely cultivated on the islands.

The recently discovered palm tree Jailoloa halmaherensis is endemic to Halmahera.

The ecoregion is home to 38 mammal species. Seven species are endemic – the ornate cuscus (Phalanger ornatus), Rothschild's cuscus (Phalanger rothschildi), Gebe cuscus (Phalanger alexandrae), blue-eyed cuscus (Phalanger matabiru), masked flying fox (Pteropus personatus), Obi mosaic-tailed rat (Melomys obiensis), and Molaccan prehensile-tailed rat (Rattus morotaiensis). Cuscuses are arboreal marsupials with origins in Australasia.