Fans will have to wait until the end of the day to purchase the new tune as it'll be sold exclusively on iTunes beginning midnight. The 10-year-old songstress is also expected to plug the club-ready song with a performance on an upcoming episode of "The Oprah Winfrey Show."
Smith previewed "21st Century Girl" in late January when she recorded a video message from the set of the song's music video. Similar to "Whip My Hair," the new tune finds the pop star ready to bring fans to the dance floor while proclaiming her youth. "21st-century girl/ I do what I like/ 21st-century girl/ I'm taking you for a ride/ 21st-century girl/ Gonna live it up/ Just live it up," Willow sings in what appears to be the song's hook.