Louis was joined at the nuptials of Johannah Poulston and her long-term partner Daniel Deakin in Manchester, North West England by his bandmates Harry Styles, Liam Payne and Niall Horan, though Zayn Malik did not appear to be in attendance, reported Daily Mirror.
Louis, who donned a blue suit, was also joined by his girlfriend Eleanor Calder, who was one of Johannah's bridesmaids.
Harry kept up his rock star persona with an all black ensemble and left his shirt unbuttoned, exposing his chest tattoos.
Also looking dapper was Niall, who wore a striped shirt and green tie for the happy occasion.