Kinnaman restarted his acting career in 2002. While studying at drama school, Kinnaman featured in several films such as Hannah med H and God Save the King (Swedish: Tjenare kungen). He also worked on productions staged at the Backa Theatre in Gothenburg. He graduated from Malmö Theatre Academy in 2007 and started working at the Gothenburg City Theatre. In the same year, he attracted the attention of Swedish media with the role of Raskolnikov in a stage adaptation of Crime and Punishment. Kinnaman went on to star in nine Swedish films in 14 months. In 2009, he starred in the film In Your Veins (Swedish: I skuggan av värmen) and played the role of a police informant in six films of the Johan Falk film series. He was cast in the film Easy Money (released January 2010), which brought him mainstream attention in Sweden and at the international film market, and also earned him a Guldbagge Award in the Best Actor category.

Looking to expand his acting career, Kinnaman hired an agent in the United States. It was announced in the spring of 2010 that he would be making his international film debut in the thriller The Darkest Hour, which began filming in Moscow in June 2010 and was released in December 2011. Between April 2011 and August 2014, Kinnaman had a 4-season starring role as Detective Stephen Holder in the AMC television series The Killing, based on the Danish television series Forbrydelsen. Kinnaman was one of the contenders for the lead roles in Thor (2011) and Mad Max: Fury Road (2015). Although Kinnaman said that he is eager to work and become recognized in the U.S., he added that “I absolutely don’t feel that I have to take any role that I can get just because it is the United States. I’m looking for something interesting, I’m still young in my artistry, and I must dare to do things even when there’s a risk for failure”.

In 2012, Kinnaman reunited with Easy Money director Daniel Espinosa in the latter’s Hollywood debut, Safe House, and also starred in the indie film Lola Versus. On 3 March 2012, it was confirmed that Kinnaman would play the lead role of Alex James Murphy/RoboCop in the remake of 1987’s RoboCop. The film was released in February 2014. In 2015, he starred in the action thriller Run All Night and mystery drama Child 44. In 2016, Kinnaman played Rick Flag Jr. in the Warner Bros. and DC Comics adaptation of Suicide Squad, directed by David Ayer. He also starred in the independent drama-thriller film Edge of Winter, where he plays Elliot Baker, a father of two who takes his children on a shooting trip that goes wrong. The film was released on demand on 27 July, and in select theatres on 12 August.

Since 2016, Kinnaman has been cast in four series on several streaming television networks. He played Governor Will Conway in Seasons 4 and 5 of the U.S. version of House of Cards on streaming service Netflix. Kinnaman also played the protagonist Takeshi Kovacs in Netflix’s Altered Carbon, an adaption to Richard K. Morgan’s hardboiled cyberpunk science fiction novel of the same name; the first season of the Netflix science fiction series debuted on 2 February 2018. On 8 February 2018, it was announced that the actor was cast as Erik in the Amazon Prime Video series Hanna, an adaptation of the 2011 action film of the same name. The first season was released on 29 March 2019. In August 2018, Kinnaman was cast as Edward Baldwin in Ronald D. Moore’s Apple TV+ alternate history space drama series, For All Mankind.

In 2019, Kinnaman starred in Andrea Di Stefano’s action thriller The Informer. Kinnaman’s’s forthcoming films include, Jérémie Guez’s crime drama The Sound of Philadelphia and Yuval Adler’s post-war thriller The Secrets We Keep.