Rising to prominence for playing Mickey Smith in Doctor Who (2005–2010),[2] he received critical acclaim for writing, directing, and starring in the teen crime drama films Kidulthood (2006), Adulthood (2008) and Brotherhood (2016) and the BBC Three television pilot West 10 LDN (2008).

Following Kidulthood, Clarke founded the company Unstoppable Film and Television, which he ran with his friend and fellow actor Jason Maza, and they have written, directed, and starred in several productions.

Clarke has also acted on the stage, and won the Laurence Olivier Award for "Most Promising Newcomer" in 2003 for his performance in the play Where Do We Live at the Royal Court Theatre.

Clarke wrote the film based on his own experiences growing in Ladbroke Grove, which he began developing with director Menhaj Huda and producer George Isaac.

[20] Following his BAFTA win, Clarke appeared in low-budget and commercially unsuccessful British films such as Heartless, Doghouse and Sex & Drugs & Rock & Roll (all 2009) and Centurion (2010).

Starring Emma Roberts, Tamsin Egerton, Ophelia Lovibond, Shanika-Warren Markland, Mandy Patinkin, Helen McCrory, Kevin Smith, Susannah Fielding, Camille Coduri and Clarke, 4.3.2.1. received generally mixed to negative reviews but was a decent box office success in the UK and overseas DVD sales.

[21] Following 4.3.2.1., Clarke continued to either co-write or star in more mainstream British films including Fast Girls, a sports film about two women and their race and personal differences as they become professional sprinters and join the British relay team for a World Championship event, and Storage 24, a science fiction-horror about a group of people become trapped inside a storage facility with a highly unwelcome guest.

After an uncredited and deleted role in the 2012 Marvel Comics Ghost Rider: Spirit of Vengeance, in 2013, Clarke played Thomas Harewood, a family man with a wife and a young daughter, in Star Trek Into Darkness.

[26][27][28][29] After years of reluctance, in 2016, Clarke returned to write, direct, co-produce and star in Brotherhood, a sequel to Adulthood and the third and final instalment in his Hood Trilogy.

In 2018, Clarke co-created, co-wrote and co-starred in the Sky One police procedural series Bulletproof, alongside Ashley Walters.

The series follows NCA detectives, and best friends, Aaron Bishop (Clarke) and Ronnie Pike Jr. (Walters), who investigate some of the country's most dangerous criminals, including traffickers, drug dealers and armed robbers, while being overseen by their boss Sarah Tanner (Lindsey Coulson).

However, prior to the fourth episode's broadcast on 29 April, The Guardian reported that Clarke was the subject of allegations of sexual harassment and intimidation by 20 women,[45] which he denied.

Clarke was overseeing the adaptation, his first major project for children, through his production company, but it ended up being transferred to New Pictures and is set to debut on CBBC, sometime in 2025.

The second was the coming-of-age school-based drama series Boarders for BBC Three, which Clarke created from scratch, after reading a newspaper article about a scholarship scheme for underprivileged young black teenagers.

[7] The actress Jing Lusi, who appeared with Clarke in the film SAS: Red Notice, alleges that he sexually propositioned and threatened her.

[9][8][52][53] The following day, ITV announced that it would not broadcast the final episode of Viewpoint, in which Clarke starred,[54] and international distribution of the series was suspended.

[55][56] Industry Entertainment declared they would no longer be representing Clarke and Sky immediately halted his involvement in any future productions.

[9][57] Clarke issued a statement through the PA news agency denying "any sexual misconduct or criminal wrongdoing" but conceding that one allegation was true, that he had repeatedly made remarks on the buttocks of an employee, Helen Atherton, who was art director on Brotherhood.

"[65] On 19 July 2023, it was revealed that Clarke was taking High Court action to seek approximately £10m in damages from The Guardian over eight articles.

In November, Mr Justice Johnson ruled that the Guardian's reporting may be interpreted as defamatory, allowing Clarke to bring forward a libel case.