[1] McLaughlin was born on 21 October 1982 in Galliagh, Derry, Northern Ireland, and grew up there in a republican family; her aunt is Martina Anderson.

She went on to study Irish History and Politics at the further education institution North West Regional College, and complete a bachelor's degree in Community Development at Ulster University.

[9] In March 2017, she was elected as a Member of the Legislative Assembly (MLA) for Foyle winning the seat previously held by former deputy First Minister Martin McGuinness.

[17] In April 2020, McCallion was elected to the 26th Seanad in the Republic of Ireland, topping the poll on the Industrial and Commercial Panel with 95,000 votes on the first count.

[18][19] In October 2020, it was revealed that three Sinn Féin bank accounts which had erroneously received UK government COVID-19 small business grants had failed to return them promptly.