[1] Before becoming an MP, Ewing was a European Community competition lawyer in Brussels and ran a small legal practice.

She has been involved in a number of Parliamentary campaigns, including fighting for the rights of people with Hepatitis C, and working to gain a public enquiry into the events at Princess Royal Barracks, Deepcut, where James Collinson, a constituent, died on 23 March 2002.

In the 2005 election, following a boundary revision, she contested the new constituency of Ochil and South Perthshire, losing to the Labour party candidate, Gordon Banks.

She sought to become SNP candidate for Moray in the 27 April 2006 Scottish Parliament by-election to succeed her late sister-in-law, Margaret Ewing.

She is famed due to an incident that occurred on 16 December 2004, whereby the Deputy Speaker removed her from the House as she refused to apologise for calling the then Defence Secretary Geoff Hoon a "back-stabbing coward"[12] during exchanges over Geoff Hoon's plans to merge Scottish Regiments, including the Black Watch.

[15] On 20 April 2023, after a particularly robust intervention from Fergus Ewing on the subject of gas extraction, she had to remind him officially about treating fellow members with respect.