West Donegal was a UK Parliament constituency in Ireland, returning one Member of Parliament from 1885 to 1922.

Prior to the 1885 United Kingdom general election the area was part of the Donegal constituency. From 1922, on the establishment of the Irish Free State, it was not represented in the UK Parliament.

This constituency comprised the western part of County Donegal, consisting of the barony of Boylagh and that part of the barony of Kilmacrenan contained within the parishes of Clondahorky, Gartan, Kilmacrenan, Mevagh, Raymunterdoney and Tullaghobegly and the townlands of Ballybolander, Boheolan, Cabra Brook, Cabra Glebe, Carnatreantagh, Carrick, Carrickyscanlan, Cloncarney, Dromore, Drumcavany, Keeloges, Maghernagran, Pollans, Roshin, Stackarnagh, Temple Douglas, Treanbeg and Tullanascreen in the parish of Conwal.

Note:-

• ¹ Not an election, but the date of a party change. The Irish Parliamentary Party had been created in 1882, on the initiative of Charles Stewart Parnell's Irish National League. Both the IPP and the INL split into Parnellite and Anti-Parnellite factions, in December 1890. The Parnellites remained members of the Irish National League after the split and the Anti-Parnellites organised the Irish National Federation in March 1891. The two organisations and the United Irish League merged in 1900, to re-create the Irish Parliamentary Party.
• ² Date of polling day. The result was declared on 28 December 1918, to allow time for votes cast by members of the armed forces to be included in the count.