In 2005, Rigby got the role as Hannah Ashworth in Hollyoaks at the age of 15. She was given praise and recognition for her anorexia storyline, in which she was nominated for various awards including the British Soap Award for Best Actress in 2008.

Her portrayal of Hannah Ashworth's battle with anorexia attracted praise. The Daily Mail's television critic, Jaci Stephen, wrote on 24 November 2007 that the Hollyoaks storyline had "taught her more than any drama or documentary on anorexia has ever done". Stephen also admitted some of Hannah's scenes had moved her to tears. She won best storyline for Hannah's eating disorder at the annual Hollyoaks awards. She was up against John Paul and Craig's affair, the "Who pushed Clare?" storyline, and Kris and Jess's relationship. At the All About Soap Bubble Awards in April 2008, Rigby won an award for the 'I'm a Survivor' (for the bravest soul in soap) category.

In July 2010, Rigby made her debut in the West End psycho-sexual thriller musical Wolfboy. She had a non-singing part, playing the role of nurse Cherry. She received positive feedback from critics.

In 2011, Rigby starred as Brandy Mulligan in online series Becoming Human. 2011 also saw Rigby make her film debut in British horror Demons Never Die, and in September of the same year she had a minor role in the first episode of C4 comedy Fresh Meat as Rachel.

In December 2011, it was announced that Rigby would be starring in brand new six-part drama series Prisoners' Wives along with Jonas Armstrong. The show's first episode aired on 31 January 2012 with Rigby playing Gemma Roscoe, a young pregnant girl whose life falls apart when her husband is arrested for murder. In March 2012, she had a guest role in Pramface as Mike's blind date Carrie-Ann. In June 2012, it was announced that she had scored the female lead in The Physician alongside Ben Kingsley, the film was released in late 2013. Also in 2013, she made her US film debut with a minor role in The Counsellor.

In 2013, Rigby appeared in episode four of Ripper Street as Lucy Eames, and in episode one of The Job Lot. In April 2013 it was announced that Rigby was cast in a lead role as the Red Queen in the U.S. television series Once Upon a Time in Wonderland.

In 2014 she starred in the remake of Endless Love and also played the female lead in the British crime film Plastic which is based on a true story, about a group of English university students were running a successful credit card scam.

In March 2015, Rigby worked alongside James Franco in the movie adaption of his book Actors Anonymous. It was released in 2017.

In 2016, Rigby confirmed that she doesn't have social media as she stated 'I'm super private and keep myself to myself.'

In September 2017, Rigby joined the cast of comedy film The Festival.