Cavan was a parliamentary constituency represented in Dáil Éireann, the lower house of the Irish parliament or Oireachtas from 1921 to 1977. The method of election was proportional representation by means of the single transferable vote (PR-STV).

From 1921 to 1923, Cavan elected 3 deputies (Teachtaí Dála, commonly known as TDs). This was increased to 4 with effect from the 1923 general election, and reduced to 3 with effect from the 1961 general election to 1977.

At the 1977 general election, the Cavan constituency was combined with Monaghan to form the new 5 seat Cavan–Monaghan constituency.^[1]

Throughout its existence, the constituency consisted of the entire administrative county of Cavan.^{[2][3][4][5][6][7]}

Note: The columns in this table are used only for presentational purposes, and no significance should be attached to the order of columns. For details of the order in which seats were won at each election, see the detailed results of that election.

• Politics of the Republic of Ireland
• Historic Dáil constituencies
• List of Dáil by-elections
• Elections in the Republic of Ireland