Khuzestan province (also spelled Xuzestan; استان خوزستان Ostān-e Xūzestān) is one of the 31 provinces of Iran. It is in the southwest of the country, bordering Iraq and the Persian Gulf. Its capital is Ahvaz and it covers an area of . Since 2014, it has been part of Iran's Region 4.
At the 2006 National Census, Khuzestan province had a population of 4,192,598 in 862,491 households. The following census in 2011 counted 4,531,720 people in 1,112,664 households. At the most recent census conducted in 2016, the province had a population of 4,710,509 in 1,280,645 households.
One of the most important regions of the Ancient Near East, Khuzestan comprises much of what historians refer to as ancient Elam, whose capital was in Susa. The Achaemenid Old Persian term for Elam was Hujiyā when they conquered it from the Elamites, which is present in the modern name. Khuzestan, meaning "the Land of the Khuz", refers to the original inhabitants of this province, the "Susian" people (Old Persian "Huza" or Huja, as in the inscription on the tomb of Darius the Great at Naqsh-e Rostam). They are the Shushan of the Hebrew sources where they are recorded as "Hauja" or "Huja". In Middle Persian, the term evolves into "Khuz" and "Kuzi". The pre-Islamic Partho-Sasanian inscriptions gives the name of the province as Khwuzestan.
The seat of the province has for most of its history been in the northern reaches of the land, first at Susa Shush) and then at Shushtar. During a short spell in the Sasanian era, the capital of the province was moved to its geographical center, where the river town of Hormuz-Ardasher, founded over the foundation of the ancient Hoorpahir by Ardashir I, the founder of the Sasanian Dynasty in the 3rd century CE. This town is now known as Ahvaz. However, later in the Sasanian time and throughout the Islamic era, the provincial seat returned and stayed at Shushtar, until the late Qajar period. With the increase in the international sea commerce, arriving on the shores of Khuzistan, Ahvaz became a more suitable location for the provincial capital.