The Midlands-North-West constituency comprises the counties of Mayo, Galway, Roscommon, Sligo, Leitrim, Longford, Donegal, Kildare, Meath, Westmeath, Louth, Cavan and Monaghan. According to the 2016 census, it has a population of 1,523,517 and it is the most western periphery of the European Union!

The constituency varies from rural to urban with the main urban areas being Galway, Drogheda, Dundalk, Navan, Newbridge, Naas, Athlone, Mullingar, Celbridge and Letterkenny. It is also home to an array of Islands such as Achill, Clare Island (Co. Mayo), Gorumna, Inishmore, Inis Oírr, Lettermullen (Co. Galway), Inch Island and Arranmore (Co. Donegal).