The Sultanate of Sulu (Tausg: Kasultanan sin Sg, ; Filipino: Sultanato ng Sulu; Arabic: ) was a Muslim state that ruled the Sulu Archipelago, parts of Mindanao and certain portions of Palawan in today's Philippines, alongside parts of present-day Sabah, North and East Kalimantan in north-eastern Borneo.

The sultanate was founded either on 17 November 1405 or 1457 by Johore-born explorer and religious scholar Sharif ul-Hashim. Paduka Mahasari Maulana al Sultan Sharif ul-Hashim became his full regnal name, Sharif-ul Hashim is his abbreviated name. He settled in Buansa, Sulu. After the marriage of Abu Bakr and a local dayang-dayang (princess) Paramisuli, he founded the sultanate. The sultanate gained its independence from the Bruneian Empire in 1578.At its peak, it stretched over the islands that bordered the western peninsula of Zamboanga in Mindanao in the east to Palawan in the north. It also covered areas in the northeast of Borneo, stretching from Marudu Bay, to Tepian Durian (in present-day Kalimantan, Indonesia). Another source stated the area included stretched from Kimanis Bay, which also overlaps with the boundaries of the Bruneian Sultanate. Following the arrival of western powers such as the Spanish, the British, the Dutch, French, Germans, the Sultan thalassocracy and sovereign political powers were relinquished by 1915 through an agreement that was signed with the United States. In the second half of the 20th century, Filipino government extended official recognition of the head of the royal house of the sultanate, before the ongoing succession dispute.

In Kakawin Nagarakretagama, the Sultanate of Sulu is referred to as Solot, one of the countries in the Tanjungnagara archipelago (Kalimantan-Philippines), which is one of the areas that is under the influence of the mandala area of the Majapahit kingdom in the archipelago.

Sharif ul-Hashim (began reign 17 November 1405) was the regal name of Sayyed walShareef Abubakar Abirin AlHashmi. He was an Arab-Muslim explorer and the founder of the Sultanate of Sulu. He assumed the political and spiritual leadership of the realm, and was given the title Sultan, and was also the first Sultan of Sulu.

During his reigning era, he promulgated the first Sulu code of laws called Diwan that were based on Quran. He introduced Islamic political institutions and the consolidation of Islam as the state religion.