Irvine earned a reputation as a Method actor after he went for two months without food, losing around two stone (13 kg), and performed his torture scene stunts in The Railway Man (2013).

[15] After completing a one-year foundation course at the London Academy of Music and Dramatic Art (LAMDA), which he attended with Sam Claflin,[16][17] Irvine spent two years posting his CV through letterboxes to get acting work.

He played Luke in the television series Life Bites[13][20] and appeared in the Royal Shakespeare Company's 2010 production of Dunsinane.

"[26] Irvine was asked to read a section of the War Horse script on camera to check his West Country accent.

[28] He spent so much time recreating the Battle of Somme scene in the film that he ended up contracting trench foot.

[30] In April 2011, Variety reported that Irvine had been cast as Pip in a 2012 film adaptation of Great Expectations by Charles Dickens.

[31][32] In October 2011, The Hollywood Reporter announced that he was set to play the young Eric Lomax in the film production of The Railway Man.

The film has been described as "a story of youth that transcends time, a gothic romance, a love triangle that involves a dark passenger.

[39] In July 2017, Irvine confirmed via his Instagram that he had joined the cast of The Last Full Measure alongside Tommy Hatto and Zach Roerig.

[3] In May 2021, Irvine was cast as Alan Scott in the HBO Max live-action television series based on Green Lantern.

[43] Irvine has been involved in trials with the Juvenile Diabetes Research Foundation (JDRF) to test an artificial pancreas,[21][44] a form of automatic glucose meter attached to a portable insulin pump.

[45][46] Irvine introduced his experiences with diabetes to Camilla, Duchess of Cornwall during a visit to the Cambridge Welcome Trust Clinical Research Facility on 7 February 2012.

[47] He was again present with the Duchess on 31 January 2013 at University College London Hospitals NHS Foundation Trust's inpatient adolescent ward, after she had become president of the JDRF in 2012.