[2][3] Black was elected as the Member of Parliament (MP) for Paisley and Renfrewshire South in 2015, when she defeated the Labour Party's Shadow Foreign Secretary Douglas Alexander.

[12] Black became a member of Parliament for Paisley and Renfrewshire South in the 2015 general election while still a final year undergraduate student at the University of Glasgow.

[18] She made her maiden speech on 14 July 2015 and this included some criticism of the government's approach to unemployment in her constituency and the growing need for food banks.

Two months following her election, she commented that the practice of making MPs vote in person, instead of electronically, was "outdated and wasted time".

[25] In a 2016 interview with Guardian journalist Owen Jones, Black labelled Westminster as an "old boys' club" and "so excluded from reality", while expressing concern about the arrogance and sexism from other MPs.

[27][28] At a public meeting in November 2016 in Aberdeenshire, Black said of the EU referendum: "If I'm honest, there was an element of holding my nose a bit when I voted Remain.

[31] Despite this, Black stood at the 2017 general election and, despite a backlash among voters to Sturgeon's plans for a second independence referendum,[32] was re-elected with a reduced majority.

[33][5][34] In April 2017, Black was heckled by protestors who were angry at the decision of the Scottish Government to close the sick children's ward at the Royal Alexandra Hospital in her constituency.

[40] In March 2020, it was reported that Black had a "blazing row" with her SNP colleague, Joanna Cherry, after the latter questioned her decision to visit a primary school with a drag queen.

[46] Black describes herself as a "traditional socialist", citing Tony Benn as her enduring political hero — despite his opposition to Scottish independence.

[50] In line with prevailing political sentiment, Black expressed her support for same-sex marriage prior to the referendum in Ireland.