Setiu is one of the districts in Terengganu, Malaysia. This district is bordered by Besut to the north, Hulu Terengganu to the south, and on the east, Kuala Nerus District.

Setiu is the second youngest and least populated district in Terengganu. Its capital is Bandar Permaisuri which also serves as its economic and commercial centre. Other towns are Chalok, Sungai Tong, Guntong and Penarik.

The district of Setiu is believed to have taken its name from a Tok Setiu, a Bugis commander who escaped the Dutch conquest of the Indonesian archipelago in the 19th century and immigrated to Terengganu. The Sultan allowed Tok Setiu and his followers to open a kampong in the plains located north of Kuala Terengganu.

Setiu, as a district, had existed as early as the 1920s, with a smaller territory than its present-day borders, during the early days of British protection over Terengganu. In 1923 it was annexed into the neighbouring Besut District until 1935, when it was made a separate district. That same year Setiu district was partitioned between Besut district and the state capital Kuala Terengganu. Setiu district with its present-day borders was reorganised in 1985, merging Mukim Merang, Mukim Hulu Nerus and Mukim Belara (portion) from Kuala Terengganu (now Kuala Nerus) and Mukim Caluk, Muki.

Majority of the inhabitants of Setiu are ethnic Malays, with remainder from the minority Chinese, Siamese and Indian communities. Most Malays in Setiu especially in the northern part speaks Kelantan-Pattani Malay however those that live in southern Setiu speaks Terengganu Malay.