Niall Horan joins Shawn Mendes on stage in surprise O2 moment

Fans were stunned as Niall Horan appeared at Shawn Mendes’ London O2 show to perform ‘This Town’ together live.

Shawn Mendes delivered a career-spanning set at London’s O2 Arena but it was a surprise appearance from Niall Horan that stole the show. The One Direction star joined Mendes on stage for an emotional duet of Horan’s hit This Town, sending fans into a frenzy.

The sold-out concert on 16 August marked the start of Mendes’ On The Road Again tour in the UK. Opening with There’s Nothing Holdin’ Me Back, Mendes treated the crowd to a mix of chart-topping singles and fan favourites from across his career. But the night took an unforgettable turn when he introduced Horan as a special guest, describing him as being like a brother.

“I met this fella years ago when I was just 16 or 17,” Mendes told the audience. “I was terrified of everything and everyone. We talk a lot but this man has been an older brother to me. I love him with all my heart.”

The pair performed with acoustic guitars as the audience sang along, with fans flooding social media to share clips of the collaboration. Many called it the highlight of the night, praising the chemistry between the two singers.

For Horan, the appearance was a rare return to the O2 stage outside of his solo tour schedule, while for Mendes it underscored the personal connections that shaped his music. Mendes spoke on stage about rediscovering his passion for songwriting during the making of his latest self-titled album, saying it reminded him why he began making music in the first place.

The European leg of the On The Road Again tour continues through August, with stops in Amsterdam, Zurich, Madrid and Lisbon, before wrapping at Munich’s Superbloom Festival on 31 August. Mendes will then head to North America in September and October for a string of sold-out shows.

The O2 performance set the tone for a tour that is already drawing acclaim, with the surprise guest slot adding an extra spark to an unforgettable opening night.