Buffon joined Juventus from Parma in 2001 for a world-record fee for a goalkeeper of £32million.
The 29-year-old Italian World Cup winner has been linked with a move away from the club in recent months.
Buffon told the club’s official website: “It is an important day for me, because I have written a new page in my career and life.
“The decision to stay is in line with what I decided last year which confirms my loyalty to this team, to this company and to Juventus fans who have never failed to show their affection for me.
“The project that I have seen for Juventus is convincing because the company has set important goals in which I believe, and because it creates the conditions for an increasingly stimulating relationship.”
