The Metropolitan Borough of Wigan is a metropolitan borough of Greater Manchester, England. It is named after its largest town, Wigan, but covers a far larger area which includes the towns of Atherton, Ashton-in-Makerfield, Golborne, Hindley, Ince-in-Makerfield, Leigh and Tyldesley. The borough also covers the villages and suburbs of Abram, Aspull, Astley, Bryn, Hindley Green, Lowton, Mosley Common, Orrell, Pemberton, Shevington, Standish, Winstanley and Worsley Mesnes. The borough is also the second-most populous district in Greater Manchester.

The borough was formed in 1974, replacing several former local government districts. It is the westernmost part of Greater Manchester and is bordered by the Greater Manchester boroughs of City of Salford and Bolton to the east, the Cheshire borough of Warrington to the south, the Merseyside borough of St Helens to the south west, and the Lancashire boroughs of West Lancashire to the west and Chorley to the north.

Wigan metropolitan borough was created on 1 April 1974 by the Local Government Act 1972. It was formed from the former county borough of Wigan along with other local government units from the administrative county of Lancashire. These were the Municipal Borough of Leigh, the urban districts of Abram, Aspull, Atherton, Hindley, Ince-in-Makerfield, Orrell, Standish and Tyldesley. Ashton-in-Makerfield except for the parish of Seneley Green, the Golborne Urban District except for the parish of Culcheth and Glazebury in Warrington, the Higher End part of Billinge and Winstanley Urban District and the civil parishes of Haigh, Shevington and Worthington from the Wigan Rural District were included.

Before its creation, the name Wigan-Leigh was used in the Redcliffe-Maud Report. It was also suggested that the new metropolitan borough be named Makerfield. However, both names were rejected by a vote of 12 to 2. According to an opinion poll in 2003, 26% of 299 residents surveyed felt they belonged "very strongly" or "fairly strongly" (4% very strongly) to Greater Manchester, 64% (28% very strongly) to the borough of Wigan, and 63% (31% very strongly) to Lancashire.

The metropolitan borough was created from a highly industrialised area of Lancashire that was part of the Lancashire Coalfield and had an important textile industry.

Wigan borough covers an area of 77 square miles (200 km²), and is the 9th-largest metropolitan borough (out of 36) in England. The borough is the most northwestern in Greater Manchester. Within Greater Manchester, it borders the Metropolitan Borough of Bolton to the north-east and east, and the City of Salford to the east. Outwith Greater Manchester, in the south it borders Warrington (a unitary authority in Cheshire); to the south-west it borders the Metropolitan Borough of St Helens in Merseyside. To the west, it borders the West Lancashire borough, and to the north it borders the Chorley borough, both in Lancashire.

Wigan borough has seven Local Nature Reserves: including Wigan Flashes LNR, Borsdane Wood LNR, between Hindley and Aspull, Greenslate Water Meadows LNR within Orrell Water Park in Orrell, Low Hall LNR between Hindley and Platt Bridge, Pennington Flash LNR, Kirkless LNR at Ince and Three Sisters LNR, Ashton-In-Makerfield.

For 12 years from the creation of Greater Manchester in 1974, the borough had a two-tier system of local government, and Wigan Council shared power with the Greater Manchester County Council. The county council was abolished in 1986 by the Local Government Act 1985. Since April 2011, some of the borough's responsibilities have been pooled with neighbouring authorities and subsumed into the Greater Manchester Combined Authority, which covers ten boroughs including Wigan.