Map - Daman and Diu (Union Territory of Damān and Diu)

Daman and Diu was a former union territory in northwestern India. With an area of 112 km2, it was the smallest administrative subdivision of India on the mainland. The territory comprised two districts, Damaon and Dio island, geographically separated by the Gulf of Khambat. The state of Gujarat and the Arabian Sea bordered the territory. A Portuguese colony since the 1500s, the territories were taken by India with the Annexation of Goa in 1961. Daman and Diu were administered as part of the union territory of Goa, Daman and Diu between 1961 and 1987, after the Goa Opinion Poll they became a separate union territory. In 2019, legislation was passed to merge the union territory of Daman and Diu with its neighbouring union territory, Dadra and Nagar Haveli, to form the new union territory of Dadra and Nagar Haveli and Daman and Diu with effect from 26 January 2020.

For over 450 years, the coastal enclaves of Daman (Portuguese: Damão) and Diu on the Arabian Sea coast were part of Portuguese India, along with Goa and Dadra and Nagar Haveli. Goa, Daman and Diu were incorporated into the Republic of India on 19 December 1961, by military conquest. Portugal did not recognise the Indian annexation of these territories until the Carnation Revolution of 1974. The territory has also been ruled by Kolis.

The territory of Goa, Daman and Diu was administered as a single union territory until 30 May 1987, when Goa was granted statehood, leaving Daman and Diu as a separate union territory. Each enclave constituted one of the union territory's two districts. Daman and Diu are approximately 650 kilometres away from each other by road.

On 3 November 2019, Daman Collector Rakesh Minhas issued a Section 144 order banning peaceful assembly of four or more persons, slogan-shouting and the use of loudspeakers across the entire district and ordered the conversion of Government High School, Bhimpore and the Government Sarvottam High School, Moti Daman into 'temporary jails'. This was in response to a land ownership dispute between the local indigenous fishing community and the local administration that had confiscated their land and bulldozed their homes. The ensuing 2019 Daman Indigenous Land Clearing Protests resulted with the detention of 70 protesters in the 'temporary jails' and another 8 arrests. Few of the adivasi fisherfolk were rehoused whilst most languished traumatised and homeless on the streets near the rubble of their razed homes.

In December 2019, the Parliament of India passed legislation to merge Daman and Diu with the nearby union territory of Dadra and Nagar Haveli to create a new union territory to be known as Dadra and Nagar Haveli and Daman and Diu.