“Diamond Heart” is the third and final chapter of the World of Walker trilogy, with “All Falls Down” being the first chapter and “Darkside” being the second. The single is by Norwegian DJ and music producer Alan Walker and features Sophia Somajo. This song was first debuted at Tomorrowland Belgium 2017 and was released on September 28th, 2018.

The song features an un-credited song writing appearance from renowned singer-songwriter Sia who composed the original demo of the song, alongside Thomas Troelsen. The song was originally sparked in sessions with David Guetta for his 2018 comeback album 7, but was unfortunately never considered.