The stars were spotted by fans who attended Grande’s first London show on the Sweetener tour.
“HARRY STYLES IS LITERALLY 5 METRES AWAY FROM ME,” a Twitter user wrote, later sharing photos and videos of Styles and Brown chatting and dancing at the concert.
While Grande performed her hit “Dangerous Woman” both Styles and Brown started dancing with each other.
“Enjoy this video of Harry Styles and Millie Bobby Brown dancing,” the same Twitter user shared. In another video the user captured, the pair could be seen speaking to one another during a different song.
The former One Direction band member’s outing comes just days after it was reported he turned down the role of Prince Eric in Disney’s live-action remake of The Little Mermaid, despite being in talks for over a month.
“While he is a fan of the project, he has respectfully declined the offer,” a source close to the film told PEOPLE last week.
Disney has not commented on who is being considered to play the handsome prince.