[1] In the 2007 Scottish election, she was an SNP candidate for the Edinburgh Central constituency, but failed to win the seat, coming third.

Somerville was re-elected to the Scottish Parliament in the 2021 election, and in Sturgeon's third government, she was appointed Cabinet Secretary for Education and Skills.

[4] She was educated at Kirkcaldy High School, before attending the University of Strathclyde from 1992 to 1996, graduating with a BA (Hons) in Economics and Politics.

On 31 August 2007, Stefan Tymkewycz resigned his seat in the Scottish Parliament representing the Lothians region in order to concentrate on serving as a City of Edinburgh councillor.

In February 2021, Christina McKelvie announced a short medical leave and her role was covered by Somerville as Minister for Equalities and Older People.

[10] In early 2020, Somerville announced the government would propose to amend the Gender Recognition Act 2004 of the Parliament of the United Kingdom.

[11] The bill would make it easier for people to change their name legally, drop the requirement for medical evidence and lower the age limit for applications from 18 to 16.

Somerville hoped for the bill to be passed by the end of the 5th Scottish Parliament, however, delays due to the COVID-19 pandemic have affected this ambition.

[16] Sturgeon announced her intention to form a third administration and appointed Somerville as the Cabinet Secretary for Education and Skills, succeeding John Swinney, who was mounted with pressure by opposition to resign.

[21] In June 2021, Somerville revealed plans to reform the Scottish Qualifications Authority (SQA) and Education Scotland was under way.

[30] Following Humza Yousaf's successful election in March 2023 to become the Scottish National Party's leader following Nicola Sturgeon's resignation, Somerville was appointed as Cabinet Secretary for Social Justice.