Stevens's triumph marked a win for mentor L.A. Reid, who announced last week that he would be leaving the show at season's end.
Sonenclar, the 13-year-old New Yorker with a diva-esque voice often considered mature beyond her years, took second, despite being referred to as the favorite by many. She and mentor Britney Spears made a tearful exchange following the results, though the young talent took her loss admirably, and is expected to sign some sort of recording deal in the future.
Despite a strong showing during Wednesday's final performance show, five-piece girl group Fifth Harmony finished third, the girls learning of their fate about halfway through the show.
"I have a feeling that we're going to be seeing -- and hearing -- a lot from these girls in the future," said the group's mentor, Simon Cowell, who has seen a young group on the show -- One Direction, in the British version of "The X Factor" -- finish third and go on to taste success.
Speaking of 1D, the Brits performed at the "X Factor" finale, debuting the poppy new single "Kiss You" amid a video game background and an enormous pair of lips. The group was joined onstage by Pitbull, who stayed true to his partying ways with "Don't Stop the Party," the current single from his 2012 release, "Global Warming."
The top three "X Factor" acts also sang a medley of Christmas tunes. Sonenclar took on Mariah Carey's Christmas staple, "All I Want for Christmas is You," with Stevens tackling "Please Come Home for Christmas" and Fifth Harmony pulling off a well-sung "Christmas (Baby Please Come Home)." Stevens and Sonenclar later dueted on Miley Cyrus's "The Climb," a performance that highlighted Stevens's country sensibilities and showcased Sonenclar's big voice.