updated 08/04/2011 AT 2:00 PM ET
•originally published 08/04/2011 AT 2:25 PM ET
Now, the 21-year-old singer will be joining his childhood crush on her European tour starting Oct. 16, he tells PEOPLE.
“It’s a dream come true,” says Jonas, who will be opening for Spears and promoting his upcoming solo album Fastlife, to be released Oct. 11.
“She was the first girl I ever had a poster on my wall of, and her album was the first CD I ever bought,” says Jonas. “It’s so funny to think I had that on my wall and here I am about to perform with her.”
Jonas first met Spears, 29, at an awards show a few years ago and says, “She’s a very sweet lady.”
He’ll join Spears’s Femme Fatale tour on Aug. 5 for one date in the U.S., then open 10 shows in Europe, with performances in Sweden, Germany, the Netherlands, France, Ireland and the United Kingdom.
“I’m really looking forward to being part of this,” he says.
“I’ll be playing more music than I have the past few times I’ve performed live so far,” he adds. “It’s going to be really fun to perform some of my music from the album.”