Western New Guinea, also known as Papua, Indonesian New Guinea, or Indonesian Papua, is the western, Indonesian half of the island of New Guinea. Since the island is alternatively named as Papua, the region is also called West Papua (Indonesian: Papua Barat).

Lying to the west of Papua New Guinea and considered a part of the Australian continent, the territory is almost entirely in the Southern Hemisphere and includes the Schouten and Raja Ampat archipelagoes. The region is predominantly covered with rainforest where traditional tribes live, including the Dani of the Baliem Valley. A large proportion of the population live in or near coastal areas. The largest city is Jayapura.

In the late 1940s, territories of the Dutch East Indies became the independent country of Indonesia, with the exception of Western New Guinea. The Dutch, however, retained sovereignty over Western New Guinea (Dutch New Guinea) until the New York Agreement on 15 August 1962, which granted the region to Indonesia. The region became the province of Irian Barat (West Irian) before being renamed Irian Jaya (literally "Glorious Irian") in 1973 and Papua in 2002. The following year, a second province was created from the western part of Papua Province; this was called West Papua, with its administrative capital as Manokwari. Both provinces were granted special autonomous status by Indonesian legislation. In November 2022 three additional provinces were created from parts of Papua Province – Central Papua, Highland Papua and South Papua –, while another additional province, Southwest Papua, was created from part of West Papua Province; these received the same special autonomous status as (the residual) West Papua and Papua Provinces, the latter now reduced to northern Papua and the groups of islands in Cenderawasih Bay.

In 2020, West Papua and Papua provinces had a census population of 5,437,775, the majority of whom are Papuan people; the official estimate as at mid 2022 was 5,601,888.

The official language is Indonesian, with Papuan Malay probably the most used lingua franca. Estimates of the number of local languages in the region range from 200 to over 700, with the most widely spoken including Dani, Yali, Ekari and Biak. The predominant official religion is Christianity, followed by Islam. The main industries include agriculture, fishing, oil production, and mining.