In October, the "Baby" hitmaker thrilled the crowd at Los Angeles' Staples Center by bringing the 10-year-old onstage to join him for a rendition of her hit track, "Whip My Hair."
And now the young stars are joining forces again. Willow Smith said Wednesday she will be part of Bieber's European trek, which starts in March.
On Twitter, she wrote, "Got news that my big bro Justin Bieber invited me on his European tour in March. So exciting! Maybe I'll let (brother) Jaden come. LOL."
Bieber confirmed the news by re-tweeting Willow's message and teasing fans that he has some extra surprises in store for his "My World Tour," writing, "Willow get ready... I got more surprises coming."
Bieber also teamed up with Willow's older brother, Jaden, earlier this year: They collaborated on a song for his "Karate Kid" movie.
Meanwhile, demand for Willow's hit single "Whip My Hair" shows no sign of slacking. The starlet tweeted that her song has reached No. 1 on the iTunes UK chart. That's already after it peaked at No. 5 on Billboard's R&B/Hip-Hop Songs chart, and its official video on YouTube has notched over 24 million views.