[4] She began auditioning and dividing her time between England and home, taking part in theatrical productions and working as a dancer for promotions and pantomimes.

[5][6] She moved around in search of employment, also working as a barista and at one point taking on a corner shop, which failed as a business.

[4] Between 2012 and 2015, O'Donnell played her first significant role as Eva Maguire, one of the main characters of the BBC2 NI series 6Degrees,[7] after the end of which she took part in the film Urban & the Shed Crew, by Candida Brady.

In 2018, she starred in a theatre production I Told My Mum I Was Going on an RE Trip, by Julia Samuels, playing an underage girl who decides to undergo an abortion.

[9] O'Donnell landed the role of Michelle Mallon in Derry Girls, a sitcom by Channel 4, which gained international fame.