[9] After graduating, Idris continued his training at Identity School of Acting in London alongside the likes of John Boyega, Letitia Wright, and Malachi Kirby.

At Brunel, Idris met actress Cathy Tyson, who encouraged him to meet Ade Solanke and audition for a part in her play, Pandora's Box.

Idris's breakout role is Franklin Saint, an ambitious 19-year-old drug dealer in Los Angeles, in the FX crime drama Snowfall from John Singleton, which debuted in July 2017.

The first season of Snowfall — set in 1983 as the United States is on the verge of the crack cocaine epidemic — weaves together the stories of several characters whose lives will soon collide because of drugs.

[14] Idris plays the character based on Akinnuoye-Agbaje, who, like many Nigerian people in the late 20th century, was "farmed out" to a white family in the UK in the hopes of a better life, while Beckinsale portrays his strict foster mother.

[19] On 7 April 2023, Deadline announced that Idris will star alongside Brad Pitt in the upcoming film F1 for Apple TV+, directed by Joseph Kosinski.