The Zanzibar Revolution (Arabic: ثورة زنجبار, romanized: Thawrat Zanjibār) occurred in January 1964 and led to the overthrow of the Sultan of Zanzibar and his mainly Arab government by the island's majority Black African population.

Zanzibar was an ethnically diverse state consisting of a number of islands off the east coast of Tanganyika. It had become fully independent in 1963, with responsibility for its own defence and foreign affairs, as a result of Britain giving up its protectorate over it. In a series of parliamentary elections preceding this change, the Arab minority succeeded in retaining the hold on power it had inherited from Zanzibar's former existence as an overseas territory of Oman.

Frustrated by under-representation in Parliament, despite winning 54 per cent of the vote in the July 1963 election, the African Afro-Shirazi Party (ASP) early in the morning of 12 January 1964, led by John Okello, the (ASP) youth leader of the Pemba branch, mobilised around 600–800 men on the main island of Unguja (Zanzibar Island). Having overrun the country's police force and appropriated their weaponry, the insurgents proceeded to Zanzibar Town, where they overthrew the Sultan and his government. They proceeded to loot Arab and South Asian-owned properties and businesses and then rape or murder Arab and Indian civilians on the island. The death toll is disputed, with estimates ranging from several hundred to 20,000. The moderate ASP leader Abeid Karume became the country's new president and head of state.

The new government's apparent communist ties concerned Western governments. As Zanzibar lay within the British sphere of influence, the British government drew up a number of intervention plans. However, the feared communist government never materialised, and because British and American citizens were successfully evacuated, these plans were not put into effect. The Eastern Bloc powers of East Germany and the Soviet Union, along with the anti-Soviet People's Republic of China, immediately recognised the country and sent advisors.

Karume succeeded in negotiating a merger of Zanzibar with Tanganyika to form the new nation of Tanzania, an act judged by contemporary media to be an attempt to prevent communist subversion of Zanzibar. The revolution ended 200 years of Arab dominance in Zanzibar, and is commemorated on the island each year with anniversary celebrations and a public holiday.