The Kingdom of Mrauk-U (Arakanese: မြောက်ဦး ဘုရင့်နိုင်ငံတော်) was a kingdom that existed on the Arakan coastal plain from 1429 to 1785. Based in the capital Mrauk-U, near the eastern coast of the Bay of Bengal, the kingdom ruled over what is now Rakhine State, Myanmar, and the southern part of Chittagong Division, Bangladesh. Though it started out as a protectorate of the Bengal Sultanate from 1429 to 1531, Mrauk-U went on to conquer Chittagong with the help of the Portuguese. It twice fended off the Toungoo Burma's attempts to conquer the kingdom in 1546–1547, and 1580–1581. At its height of power, it briefly controlled the Bay of Bengal coastline from the Sundarbans to the Gulf of Martaban from 1599 to 1603. In 1666, it lost control of Chittagong after a war with the Mughal Empire. Its existence continued until 1785, when it was conquered by the Konbaung dynasty of Burma.

It was home to a multiethnic population, with the Buddhists making up the majority and the city of Mrauk U being home to mosques, temples, shrines, seminaries and libraries. The kingdom was also a center of piracy and the slave trade. It was frequented by Arab, Danish, Dutch and Portuguese traders.

The kingdom's official name was မြောက်ဦး ဘုရင့်နိုင်ငံတော် (English: Mrauk U Kingdom or Kingdom of Mrauk U). The Kingdom was commonly also known as Arakan during its existence.

Although Arakan kings paid tribute to the Pagan dynasty, the South was mostly free of Pagan suzerainty and largely cut off from the rest of Burma. Separated from Pagan by the Arakan Mountains, Arakan developed more independently to other Burmese regions. its capital moved from Thaibeiktaung to Dhanyawadi to Vesali before the 11th century, and then to Pyinsa, Parein, and Hkrit in the 12th century, with the capital moving to Pyinsa again in 1180, and then Launggyet in 1237.

Arakan had close contact with Bengal, coming into full contact with it as it was expanding eastwards. During the reign of King Min Hti of Arakan (1279–1374), Bengal invaded parts of Arakan sea, raiding the Hinya river at Chittagong. Following the collapse of Pagan power and the death of Min Hti, Arakan fell into an interregnum, and constant raids were conducted by both the Burmese and the Talaing. The new king who took power in 1404, Narameikhla, who was a great-grandson of Min Hti, was immediately ousted by the forces of the Burmese Crown Prince Minye Kyawswa, who captured Launggyet and forced Narameikhla to flee to the court of the Sultanate of Bengal at Gour. During Narameikhla's 24-year exile, Arakan became an extensive battleground for the Ava Kingdom and the Pegu Kingdom. The King of Ava installed his son-in-law on the throne of Arakan, bestowing him the title of Anoarahtâ. Pegu forces later captured and executed him. The power struggle ended with Razadarit coming out on top, capturing Taunggyet and installing his own governor, who was in power until 1423.

After 24 years of exile, Narameikhla regained control of the Arakanese throne in 1430 with military assistance from Bengali commanders Wali Khan and Sindhi Khan. The Bengalis who came with him formed their own settlements in the region. Narameikhla ceded some territory to the Sultan of Bengal and recognised his sovereignty over the areas. In recognition of his kingdom's vassal status, the kings of Arakan received Islamic titles, despite being Buddhists, and legalised the use of Islamic gold dinar coins from Bengal within the kingdom. The kings compared themselves to Sultans and fashioned themselves after Mughal rulers. They also employed Bengali Muslims in prestigious positions within the royal administration. Narameikhla minted his own, with Burmese characters on one side and Persian characters on the other. Despite ruling parts of Bengal, it continued to remain a protectorate of the Sultan of Bengal up until 1531.

Narameikhla founded the city of Mrauk U, which was declared the capital of the Arakanese kingdom in 1431. As the city grew, many Buddhist pagodas and temples were built. Several of them remain, and these are the main attraction of Mrauk-U. From the 15th to the 18th centuries, Mrauk U was the capital of the Arakan kingdom, frequently visited by foreign traders (including Portuguese and Dutch). The golden city of Mrauk U became known in Europe as a city of oriental splendor after Friar Sebastian Manrique visited the area in the early 17th century. Father Manrique wrote a vivid account of the coronation of King Thiri Thudhamma in 1635.

Narameikhla was succeeded by his brother, Min Khayi, who annexed Sandoway and Ramu in 1437. Min Khayi's successor, Ba Saw Phyu occupied Chittagong with the help of the Portuguese, at the beginning of his reign. Although Barbek Shah, the new Sultan of Bengal, allowed Bengal to falter, Arakan remained subordinate to Bengal until 1531.