The band - JC Chasez, Chris Kirkpatrick, Joey Fatone, Lance Bass, and Justin Timberlake - started making hits in 1995 and soon became one of the biggest music groups leading up to the millennium.
Their mega-success ended in 2001 when they parted ways to pursue other projects.
NSYNC took to social media early on Friday to share a short clip of them in the studio working on a new song together called Better Place.
The social media video included some snippets of the new song, set for release on September 29.
The almost two-minute video shows all five members of the band working through a mix in a studio.
The most famous alum of the boy band, Timberlake, appears in the clip.
The solo musician and Friends with Benefits star is seen behind the mixing desk, hinting that he might have also produced the new song.
The video also shows footage of Kirkpatrick, Chasez, Bass, and Fatone in the studio and recording booth.
"If we do this song, it's a love letter to our fans," Timberlake said.
"I would be honoured to have the group on this song."
The video ends with words from Timberlake saying to his fellow band members: "I love you guys. That's ... epic man."
The announcement video has gone viral, garnering more than 600,000 views on social media platform X, more than 4400 retweets and 88,500 likes on Instagram.
Better Place will feature on the soundtrack for Universal Studios movie Trolls Band Together, which stars Justin Timberlake as a voice actor.
The animated film will be released on November 17.
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