Mikkelsen achieved worldwide recognition for playing the main antagonist Le Chiffre in the twenty-first James Bond film, Casino Royale (2006).

[2] His other film roles include Igor Stravinsky in Coco Chanel & Igor Stravinsky (2008), Johann Friedrich Struensee in A Royal Affair (2012), his Cannes Film Festival Best Actor Award-winning performance as Lucas in the Danish film The Hunt (2012), Kaecilius in Marvel's Doctor Strange (2016), Galen Erso in Lucasfilm's Rogue One (2016), his BAFTA-nominated role as Martin in Another Round (2020),[3] Gellert Grindelwald in Fantastic Beasts: The Secrets of Dumbledore (2022), Dr Jürgen Voller in Indiana Jones and the Dial of Destiny (2023), and Captain Ludwig Kahlen in The Promised Land (2023).

A. O. Scott of The New York Times remarked that in the Hollywood scene, Mikkelsen has "become a reliable character actor with an intriguing mug" but stated that on the domestic front "he is something else: a star, an axiom, a face of the resurgent Danish cinema".

[7] In his youth, he trained as a gymnast, wanting to pursue athletics, but then studied dancing at the Balettakademien (ballet academy) in Gothenburg where he also became fluent in Swedish.

In 1999, Mikkelsen had a leading role as Lenny, a shy film expert who suffers from avoidant personality disorder, opposite Kim Bodnia in Refn's Bleeder (1999).

[11][12] In 2002, Mikkelsen had a starring role as a young doctor who falls in love with the girlfriend of one of his patients in Open Hearts which earned him both Robert and Bodil nominations in 2003 for best actor.

[18] Mikkelsen's breakthrough and his longest running role was as a sensitive policeman in Niels Arden Oplev's Danish television series Rejseholdet (Unit One) (2000–03), for which he won the 2002 Best Actor Award from TvFestival.dk.

He became more widely known internationally for his role as Tristan in Jerry Bruckheimer's production of the movie King Arthur (2004), which was a commercial success despite negative reviews.

[19] In 2006, Mikkelsen starred opposite Stine Stengade and Jana Plodková in Ole Christian Madsen's award-winning film Prag (Prague).

[20] The same year, Mikkelsen achieved his first widely acclaimed international success as Le Chiffre in the twenty-first James Bond film, Casino Royale.

[21] Roger Ebert noted the suspense during Mikkelsen's scene with Bond during the extended poker game, in which Le Chiffre weeps blood from his left eye.

"[23] In 2006, Mikkelsen also took the lead role in the Danish drama After the Wedding, which earned an Academy Award nomination for Best Foreign Film.

The New York Times remarked that on the Hollywood scene, Mikkelsen has "become a reliable character actor with an intriguing mug" but stated that on the domestic front "he is something else: a star, an axiom, a face of the resurgent Danish cinema.

"[24] In 2008, Mikkelsen portrayed Danish resistance fighter Jørgen Haagen Schmith opposite Thure Lindhardt and Stine Stengade in Ole Christian Madsen's Flame & Citron (Flammen & Citronen), a film which is loosely based on actual events involving two of the most active fighters in the Holger Danske resistance group during World War II.

[26] Michael O' Sullivan of The Washington Post likened Mikkelsen and Lindhardt's characters to Butch Cassidy and the Sundance Kid and said that it is "the story of handsome rogues with guns.

"[29] Mikkelsen then returned to violent action, collaborating once again with Refn, playing a Norse warrior in the Crusades in Valhalla Rising (2009) and Draco, a self-sacrificing leader of the king's guard in Clash of the Titans (2010).

[43] He played the villainous mayor in Doug Liman's adapted science fiction film Chaos Walking, based on Patrick Ness' trilogy novels of the same name.

[48] Mikkelsen has also appeared in Carlsberg's new 2019 UK advert, announcing that the brand's flagship beer has been rebrewed to become a Danish pilsner.

[49] Mikkelsen reunited with Thomas Vinterberg for the Danish comedy drama Another Round, which won the Academy Award for Best International Feature Film and earned Mikkelsen a BAFTA Nomination for Best Actor in a Leading Role[50][51] In November 2020, Mikkelsen was revealed to be in early talks with Warner Bros. for the role of Gellert Grindelwald in the Fantastic Beasts series from Fantastic Beasts: The Secrets of Dumbledore, in which Warner Bros. asked Johnny Depp to step down after the latter lost in a defamation trial against News Group Newspapers.