Timberlake posted a video of the group recording the track in the studio on Instagram, ahead of the song's release on Sept. 29.
"So many stars aligned that that's why I hit y'all," Timberlake says while addressing the other band members, JC Chasez, Joey Fatone, Lance Bass and Chris Kirkpatrick.
In edited snippets of his remarks, Timberlake continues, "If we do this song, it's a love letter to our fans. I would be honored to have the group on this song."
Then someone says, "Who's ready for a reunion?"
What follows is footage of the singers taking their turns in the vocal booth as Timberlake and the engineers work to perfect the track.
When it's done, Lance Bass notes it's the first finished *NSYNC tune in 23 years.
"Listen man, I love you guys. That s*** is epic, man," Timberlake says after listening to the playback.
Timberlake captioned the post, "When the stars align… got my brothers back together in the studio to work on something fun and the energy was special. Better Place is coming 9/29 LOVE Y'ALL."
"Better Place" is part of the soundtrack of Timberlake's upcoming animated film "Trolls Band Together," which is coming out in November.
*NSYNC reunited on the MTV VMAs stage Tuesday night to present Taylor Swift the best pop award for her song "Anti-Hero." The band's upcoming song was announced shortly after.