Jason Witten signs four-year extension through 2021

Cowboys weren't going to let Witten get away (1:32)

Antonio Pierce and Ryan Clark aren't surprised at all to see Jason Witten sign a contract extension with Dallas. (1:32)

FRISCO, Texas -- Jason Witten truly will be a Dallas Cowboy for life.

Witten signed a four-year extension through 2021 on Tuesday, the club announced.

The deal maxes out at $29.6 million, according to sources. It does not include more guaranteed money but gives both sides peace of mind knowing where Dallas' longtime tight end will play beyond this season.

Witten, who turns 35 in May, was entering the final year of his deal and is set to make $7.4 million in base salary and will count $12.262 million against the salary cap. The Cowboys can restructure Witten's contract and free up close to $4 million in cap space whenever they need it.

"He wants to make sure he is never not in the last year of his contract. It worked out for everybody. It helped us under the cap this year as well," Cowboys vice president Stephen Jones said, according to the Star-Telegram.

This is the fourth contract Witten has signed with the Cowboys since he was a third-round pick in 2003.

After the Cowboys' divisional-round loss to the Green Bay Packers in January, Witten said he anticipated he would return for another season, even if retirement crept into his mind. With this deal, he is showing that he is thinking of playing beyond 2017.

In Cowboys history, nobody has caught more passes (1,089), played in more consecutive games (219) or started more consecutive games (163) than Witten. By the second game of the 2017 season he will have played in more games than any player in Cowboys history. He needs 17 more receiving yards to break Michael Irvin's team mark of 11,904.

Witten needs 13 catches to move into the top five in league history, passing Hall of Famer Cris Carter (1,101). Among tight ends, only Tony Gonzalez has more catches and yards than Witten, who has played in 10 Pro Bowls.

Witten has caught at least 60 passes every season since his rookie year, finishing with 69 receptions for 673 yards and three touchdowns in 2016.

As valuable as he is on the field for the Cowboys, Witten's presence as a leader is equally as important. He is the soul of a Cowboys team that has transitioned to a young roster with players on both sides of the ball looking at him for guidance.

In the past few years, Witten's role has changed, with the Cowboys becoming more of a run-first team, but he remains one of the best do-it-all tight ends in the game with his blocking and pass-catching skills.