Belfast West was a borough constituency of the Parliament of Northern Ireland from 1921 to 1929.

It returned four MPs, using proportional representation by means of the single transferable vote.

Belfast West was created by the Government of Ireland Act 1920 and contained the Court, Falls, St Anne's, St George's, Smithfield and Woodvale wards of the County Borough of Belfast.

The House of Commons (Method of Voting and Redistribution of Seats) Act (Northern Ireland) 1929 divided the constituency into four constituencies elected under first past the post: Belfast Central, Belfast Falls, Belfast St Anne's and Belfast Woodvale.

[1] In May 1921, Dáil Éireann, the parliament of the self-declared Irish Republic run by Sinn Féin, passed a resolution declaring that elections to the House of Commons of Northern Ireland and the House of Commons of Southern Ireland would be used as the election for the Second Dáil.