Earlier this month, Bieber revealed that he has teamed up with Swift for a song that could potentially feature on his upcoming third album Believe.
"They did write a song together when they did the Punk'd episode. They actually later on went and wrote a song together and it's beautiful," Gomez said of the duet during her visit to On Air with Ryan Seacrest.
"It's amazing. I don't know if it will make the album, but if not I'm sure they'll release it at some point, because it's a really great record.
"It's kind of like... it's Taylor and Justin combined. So it's a little bit of an upbeat song, but it's very acoustic."
Gomez also talked about recently being caught on the kiss cam with Bieber during a Los Angeles Lakers game, calling it the "most humiliating thing that's ever happened to [her]".
Believe will be released on June 19.
Listen to Justin Bieber's 'Boyfriend' below: