Buffon’s new contract comes a year after he returned to Juve following a 12-month stint in France at Paris Saint-Germain.
The former Italy international goalkeeper’s new deal will come to an end exactly 20 years after he first joined Juve.
Buffon, now aged 42, has made 13 appearances in all competitions this season and holds the record for the most Serie A appearances in the club’s history.
He became the second-oldest player in Champions League history when he featured against Bayer Leverkusen in this campaign’s group stage.
After agreeing the contract extension, Buffon said: “Probably each of us hoped, and basically knew, that the thread that united us for so many years was not destined to break.”
The club added: “Super Gigi is proof that age is only a number. With today’s renewal, if it is even possible, he is even more Bianconero – and we can only be happy with it. A legend. A player, who is simply, infinite.”