Unionist Party may refer to:

• Conservative and Unionist Party, the formal name of the Conservative Party
• Liberal Unionist Party, existed from 1886 to 1912
  • Unionist government, 1895–1905, a coalition government of the two parties

• Democratic Unionist Party (DUP), the larger of the two main unionist political parties in Northern Ireland
• Ulster Unionist Party (UUP), the smaller and more moderate of the two main unionist political parties in Northern Ireland
• Progressive Unionist Party (PUP), minor loyalist party formed in 1979
• Traditional Unionist Voice (TUV), minor loyalist party formed in 2007
• Ulster Unionist Labour Association (or Labour Unionist Party)

• Protestant Unionist Party, former political party formed by Ian Paisley in 1966 out of the Ulster Protestant Action (UPA) movement
• Independent Unionist Association (or Independent Unionist Party), existed from 1937 to late 1940s
• Vanguard Unionist Progressive Party (Ulster Vanguard), existed from 1973 and 1978
• Unionist Party of Northern Ireland, existed from 1974 and 1981
• United Ulster Unionist Party, existed from 1975 and 1982, splinted from the Vanguard Progressive Unionist Party due to a disagreement over power-sharing
• Ulster Popular Unionist Party, existed from 1980 to 1995
• UK Unionist Party, existed 1995 to 2008
• Northern Ireland Unionist Party, existed 1999 to 2008

• Unionist Party (Scotland), centre-right party which existed between 1912 and 1965, the dominant force in Scottish politics until the late 1950s
• Scottish Conservative and Unionist Party, the full name of the party since 1965 more often called the Scottish Conservative Party
• Scottish Unionist Party (1986), Scottish minor party of traditionalist Unionists disillusioned with the Conservative government's signing of the Anglo-Irish Agreement

• Unionist Party (Punjab), a major political party in the former Punjab Province until 1947

• Unionist Party (Canada), existed from 1917 to 1920
• Unionest Party

• Unionist Party (Kingdom of Croatia), existed from 1861 to 1918

• Union Party (Faroe Islands)

• Unionist Party (Greenland)

• National Progressive Unionist Party

• Unionist Party (Guatemala, 1920)
• Unionist Party (Guatemala)

• Central American Unionist Party

• Unionist Party (South Africa)

• Sahaphum Party ("Unionist Party" in English)

• Unionist Democratic Union

• Union Party (United States, 1850), a political party created to support the Compromise of 1850
• Constitutional Union Party (United States), a party notable for its role in the 1860 presidential election
• Unionist politician (American Civil War)
• National Union Party (United States), a party in the free states during the American Civil War
• Unconditional Union Party, a wartime party in the border states
• Union Party (Kansas), a wartime party in Kansas

• Unionism (disambiguation)
• Unionist (disambiguation)
• Separatism