Styles looked debonair in a crisp white button-up and black suit, and added his personal fashion flair to his ensemble by wearing silver rings and tan embellished boots.
The heartthrob, who is making his big screen acting debut in the Christopher Nolan war film, also posed with the director and cast, including Cillian Murphy and Tom Hardy, for a group pic on the blue carpet.
The former One Directioner also got to reunite with Prince Harry during the premiere. The two had previously met in 2015 at the Royal Variety Performance where 1D was among the many artists to take the stage.
Earlier this month, Nolan told ET that Styles was "perfect for this part," adding, "What I was seeing [when he auditioned] was a very charismatic guy who clearly had a truthfulness and a subtlety in his ability to perform as a film actor."
For more on Styles' performance in Dunkirk, watch below. The film arrives in theaters on July 21.