It is located in the northwestern part of the country. Its population is 1,584,607 and it covers a total area of 2,114 km². The province is bordered to the east by the provinces of Mostaganem, to the south east by Mascara, to the south west by Sidi Bel Abbes, and to the west by Aïn Témouchent Province.
The province was formed from the former French department of Oran, which was maintained after independence and was transformed into a wilaya (province) by the ordnance of 1968. It inherited its current structure after the re-organization of 1974, when it lost its western and southern parts in favor of the creation of Sidi Bel Abbès Province.