Ruti Olajugbagbe, who simply goes by Ruti, said she "screamed in Tottenham Court Road station" when her agent told her the news over the phone.
"I don't really know how to explain it when I think about it and talk about it, because it's quite unbelievable for me," she told Radio 1's Newsbeat. "It's so mind-blowing. Adele was one of the big artists that I just aspired to sing like when I was younger. So the fact that it's kind of come a bit full-circle where I'm supporting her, that she wants me to be at this show, I don't really understand what's happening."
Ruti won ITV's "The Voice" in 2018, where she joined Sir Tom Jones' team and led the Welsh crooner to victory.
Shortly after winning, her winner's single "Dreams" (a cover of The Cranberries song) went to number one on the UK iTunes Store and reached number 14 on the UK Singles Chart.