The show will air on HBO Max, according to the streaming service.
Jennifer Aniston, Courteney Cox, Lisa Kudrow, Matt LeBlanc, Matthew Perry, and David Schwimmer are all set to appear in the programme.
“Guess you could call this the one where they all got back together — we are reuniting with David, Jennifer, Courteney, Matt, Lisa, and Matthew for an HBO Max special that will be programmed alongside the entire Friends library,” said Kevin Reilly, chief content officer, HBO Max and president, TBS, TNT, and truTV.
The unscripted cast reunion special, along with all 236 episodes of the Emmy-winning series, will be available to subscribers at the launch of HBO Max.
Aniston, Cox, Kudrow, LeBlanc, Perry, and Schwimmer will also executive produce the special, which is due to air in May.
It's understood the stars will each receive $2.5m to appear.
Friends, which debuted in 1994, made superstars out of the six actors and has been shown on British screens for years, gaining a new audience through on demand services.