His breakthrough in Denmark came with his portrayal of a boy with autism in A Place Nearby, co-starring with Ghita Nørby.

[2] Since then, he has played parts in a variety of movies and series, including Into the Wild, Angels in Fast Motion aka Nordkraft, Brotherhood, Love in Thoughts, Sugar Rush, Princess, Rejseholdet, Byzantium and Flame & Citron, a movie about the World War II resistance group Holger Danske, in which Lindhardt played Bent Faurschou-Hviid, co-starring with Mads Mikkelsen.

[3] He also played a role as the young Swiss Guard Lieutenant Chartrand in the 2009 film Angels & Demons, directed by Ron Howard.

[6] In 2012 Lindhardt played a role in the European-Scandinavian TV series The Spiral,[7] and in 2013 he appeared in the feature film Adieu Paris.

[9] In 2015 he played the Danish detective Henrik Sabroe opposite Sofia Helin in season 3 of the Danish-Swedish TV police series The Bridge.