Released on July 24, 2026,  Fireflies is a collaboration with chart-topping DJ, producer and longtime friend of the band, Martin Garrix. 

Fusing Bono's unmistakable vocals, U2's classic sound and Garrix's signature production, the song marks the first time all four members of U2 have appeared on a track with Garrix. Fireflies premiered live during Garrix's headline set at Belgium's Tomorrowland festival, including a surprise appearance from Edge.

In April 2026 Garrix produced  "Scars," on the band's Easter Lily EP and back in 2019  he collaborated with Bono and Edge on "We Are The People," for the UEFA Football Championship.

''Fireflies' has a very unique mood,' explained Martin. 'It's a special song we started working on six summers ago. It felt electrifying and very surreal to finally debut it at Tomorrowland with The Edge.
'I've worked with Bono and Edge before, but working with the whole band I got to get a glimpse of their chemistry and why U2 are who they are. They are incredible friends and collaborators, and it has been an absolute honour to work with them again.'

"We go back a long way with Martin,' added Edge. 'There's always a sense of adventure whenever we get together. Playing Fireflies for the first time at Tomorrowland, in front of one of the most passionate festival crowds anywhere, was such a rush... in fact I might have enjoyed it a bit too much. It reminded me of why I love playing outdoors. I like it better when there's no ceiling."