The 30-year-old singer performed his 2018 hit 'You Are The Reason' over the summer at the luxurious ceremony in the South of France, and despite enjoying the big day he insisted he wasn't given any money for his role.
He's quoted by The Sun newspaper's Bizarre column as saying: "I met Joe at The Voice Australia. He was like, 'Me and Sophie have been huge fans', and I got his number and we texted.
"Then he said, 'We've listened to You Are The Reason all through our relationship and we were wondering if you would sing it at the wedding?'
"It was very mad, there was an embargo on all cameras, so it was a really private and beautiful moment."
However, asked if he was paid for singing at the wedding, he simply replied: "No."
Calum previously confirmed his performance in July as he revealed he sang as the 'Game of Thrones' actress and the Jonas Brothers star tied the knot in a "magical" intimate ceremony at Le Chateau de Tourreau in June in Sarrians, France.
Sharing a selfie just days after the wedding, he wrote: "This weekend I had the honour of singing 'You Are The Reason' at the wedding of @joejonas & @sophiet and it was magical. Thank you both for allowing me to be part of such an incredibly special day. You are perfect for each other.(Sic) "
Sophie's maid of honour at the event was her co-star and best friend Maisie Williams, while Joe's brothers Nick and Kevin attended with their wives, Priyanka Chopra and Danielle Jonas respectively. Wilmer Valderrama and his girlfriend Amanda Pacheco were also joined at the wedding reception by fellow guests Ashley Graham and husband Justin Ervin.
Joe and Sophie legally married in May in Las Vegas and the actress previously revealed her dad was "beyond pleased" when she married Joe.
She said: "My dad was beyond pleased when I married a musician because it was always kind of, 'You have to marry a rugby player or a musician.' So I got one of them right."
