In September 2013, it was announced that O'Donnell had been cast in Hollyoaks as Peri Lomax, the youngest child of the Lomax family and would be joined by father Danny Lomax, mother Sam Lomax and sisters Leela Lomax and Tegan Lomax. Of the family's arrival, executive producerBryan Kirkwood commented: "I was conscious of the fact that Ste was languishing on his own with no family around him. I'm eager to bring in a strong female force." He also commented "the sisters will certainly be causinga lot of mischief in the village. So look out Hollyoaks! The Lomaxes are coming..." O'Donnell's character, Peri made her first appearance on the episode broadcast on 4 October 2013. On 23 November 2014, it was announced that O'Donnell's character Peri, would be involved in a teen pregnancy storyline alongside with character Tom Cunningham. The storyline was devised as an effort to promote safe sex. On the storyline O'Donnell said "Some of the scenes have been hard to tackle because I am still quite young and I’ve had to do a lot of research for them. I am younger than Peri, as she is just turning 15 and I’m only 14 myself. So I’ve done the research to help with my performances and to find out how teenagers actually do react in these situations." She also said, "When I was first told about the story, I was nervous and didn’t know what to expect, but then I had a lot of meetings about it with the show’s executive producer Bryan Kirkwood, the storyliners and the other producers. They explained it to me and made me feel a lot more comfortable about it. Now I’ve got into it, I’m very excited about the storyline and I’m really enjoying doing it." For her role as Peri, O'Donnell has been nominated twice in the Inside SoapAwards in 2014 and 2015. In August 2017, O'Donnell was longlisted for Best Young Actor at the Inside Soap Awards however she did not progress to the shortlist. O'Donnell has also been nominated for Best-On Screen partnership with Ellis Hollins, and was also nominated for Best Young Performance in 2015 and Best Young Actress at The British Soap Awards in 2016.
