Ottoman Tunisia, also known as the Eyalet of Tunis or the Regency of Tunis, was a territory of the Ottoman Empire that existed from the 16th to 19th century in what is largely present-day Tunisia.

The Ottoman presence in the Maghreb began with the conquest of Algiers in 1516 by the Ottoman Turkish corsair and Beylerbey Aruj Barbarossa (Oruç Reis). In 1534, the Ottoman Navy under the command of Kapudan Pasha Hayreddin Barbarossa, the younger brother of Aruj, attacked and captured Tunis, a territory of the Hafsid dynasty. Less than a year later in 1535, the Holy Roman Emperor Charles V sent a multinational invasion force to wrest control of Tunis, overwhelming the city's Ottoman defenders. Following the final Ottoman reconquest of Tunis from Spain in 1574, the Ottoman Empire controlled Tunis for over three centuries. The period of Ottoman rule came to an end following the French conquest of Tunisia in 1881.

Tunis was initially ruled from the Ottoman Regency of Algiers; however, the Ottomans established a separate governor (pasha) for Tunis, whose authority was to be backed by Janissaries under his command. As a result, Tunis began to function as a separate province with a considerable degree of autonomy. Although Algiers occasionally contested this, Tunisia maintained its autonomous status. Like other distant Ottoman territories, the governing councils responsible for administering the province consisted mostly of Ottoman elites - Turks, Egyptians, Albanians, etc. - from other parts of the empire. State affairs were primarily conducted in Ottoman Turkish.

At the center of what was then known as the Barbary Coast, Barbary corsairs used North African ports like Algiers, Tunis, and Tripoli as bases to target European shipping and, at the height of their power, raid ports and towns along Europe's Mediterranean coast. During these raids, Barbary pirates frequently captured European sailors and civilians, who were either ransomed or sold into slavery. For centuries, Tunis was among the principal centers of the Barbary slave trade. Eventually, a prolonged decline in raids and the increasing naval power of European states, culminating in a series of punitive wars by the United States, later joined by Sweden and the Kingdom of Sicily, brought an end to the raids and the slave trade.

By the end of the Ottoman period, Tunisia had experienced a considerable loss in its territory. The decay in Ottoman authority throughout the 18th and 19th centuries led to conflicts with rival provinces, especially Tripoli, and foreign encroachment. In the 19th century, Tunisian rulers observed the ongoing political and social reforms occurring throughout the Ottoman Empire. Inspired by the Turkish model, the Bey of Tunis began modernizing Tunisia's administration, infrastructure, and economy, though these modernization efforts were expensive and would lead to Tunisia amassing a considerable amount of foreign debt. In 1881, France used this as a pretext to establish a Protectorate, effectively taking control over the territory.

The legacy of the centuries-long period of Ottoman rule in Tunisia is evident in the presence of Tunisia's large Turkish community. Historically, mixed male descendants were known as the Kouloughlis.

In the 16th century, control of the western Mediterranean was contested between the Spaniards and the Turks, both confident due to recent triumphs and subsequent expansion. In 1492, Spain completed its centuries-long Reconquista of the Iberian Peninsula, followed by the establishment of the first Spanish settlements in America. Spain then devised an African policy, establishing a series of presidios (a type of fortification against attacks) in port cities along the African coast. The Ottoman Turks achieved their long-term ambition of capturing Constantinople in 1453, then successfully expanded further into the Balkans (1459–1482), and later conquered Syria and Egypt (1516–1517).

Turkish Barbary corsairs operated from bases in the Maghreb. Spain captured and occupied several ports in North Africa, including Mers-el-Kebir (1505), Oran (1509), and Tripoli and Bougie (1510). Spain also established treaty relations with several other ports. These agreements included Algiers (1510), which granted Spain occupation of the offshore island of Peñón de Argel. Spain also reached agreements with Tlemcen (1511), a city about 60 km inland, and with Tunis, whose Spanish alliance lasted inconsistently for decades. Near Tunis, the port of Goletta was later occupied by Spanish forces, who built a large and strong presidio there. They also constructed an aqueduct to Tunis for use by the kasbah.