The United Ulster Unionist Party was a political party which existed in Northern Ireland between 1977 and 1982.

It emerged from a division in the Vanguard Progressive Unionist Party in the late 1970s. Vanguard had traditionally opposed the concept of compulsory power sharing enshrined in the Sunningdale Agreement, but after the failure of Sunningdale the Northern Ireland Constitutional Convention was set up to provide a forum with an aim to finding a new settlement for Northern Ireland. During the proceedings the leader of Vanguard, William Craig, proposed a voluntary coalition with the Nationalist Social Democratic and Labour Party. Many in Vanguard found this anathema, including the party's deputy leader Ernest Baird and Mid Ulster MP John Dunlop. They left Vanguard and formed the United Ulster Unionist Party.

Many critics highlighted the irony of the name, given that the UUUP was a breakaway from Vanguard, itself a breakaway from the Ulster Unionist Party and there were many other Unionist parties in existence.

The UUUP did not prosper long. In the 1979 general election Dunlop held his seat but only due to an agreement with other Unionist parties to not divide the unionist vote where a nationalist might get elected. In 1982 a new Northern Ireland Assembly was established to provide a degree of scrutiny over the Secretary of State for Northern Ireland. The UUUP got a derisory vote, with even Dunlop getting barely 3% of the vote in his Mid Ulster constituency. The party soon folded. Dunlop remained as MP for Mid Ulster until the 1983 general election but did not contest his seat.