"COMING SOON," the singer-actress wrote of the mystery project.
The track appears on the girl group's Billboard 200-topping EP With YOU-th.
The track comes ahead of the boy band star's "White Christmas" collaboration with Bing Crosby.
The track will follow her chart-topping "APT." duet with Bruno Mars.
The star also gushed about her bandmates' respective solo projects.
Fans are convinced that the star is gearing up to release a solo album.
The K-pop star called the legendary vocalist his "all time favorite jazz artist."
"It's a song that will put a smile on your face," added the star.
ROSÉ, JENNIE, JISOO and LISA have all released their own music.
The duet finds the pair showing off their rap skills as a team.
