The extension, which a league source told ESPN.com's Pat Yasinskas is worth $7 million, was announced before Sunday's 45-24 win over Tampa Bay.
"Very happy to be coming back next year to play. I love everything about the Falcons and the city of Atlanta," Gonzalez said on his Twitter account Sunday.
The 35-year-old Gonzalez has enjoyed a strong season, starting every game. Entering Sunday's game, he already had topped his 2010 totals with 79 catches for 867 yards and seven touchdowns. His 79 catches rank third among NFL tight ends.
Now in his 15th season, Gonzalez was chosen to the Pro Bowl for the 12th time this season. His first Pro Bowl season came in 1999, his third season with Kansas City.
General manager Thomas Dimitroff said reaching an agreement with Gonzalez is an important first step in his dealings with the team's players who can be free agents.
"This wasn't about which free agent was the most important to secure," Dimitroff said.
"It's a good start. It makes things a lot easier to see where we're going moving forward, trying to get the rest of our deals done. It's a significant deal and it helps us gauge where we are with the rest of our financial situation."
Dimitroff said Gonzalez's excellent conditioning has helped him thrive in Atlanta as one of quarterback Matt Ryan's favorite targets.
"Tony's in such great shape and he came back this year feeling in better shape than he ever has in his golden years, so to speak," Dimitroff said. "He's very, very comfortable with this offense and with our coaching staff and with Matt and the rest of the players. I think, for him, it was really important to get this done by the end of the season so we weren't sidetracked in the offseason."
Gonzalez said this week being selected to another Pro Bowl was "an incredible honor and I'm happy."
This is the 13th straight year he's caught at least 60 passes.
Gonzalez is second on the NFL's receptions list with 1,148 catches, trailing only Jerry Rice. He is the first tight end, and 13th player in NFL history, to have more than 13,000 yards receiving and holds nearly every NFL mark for the position. He has 95 touchdown catches.
Since being traded from the Chiefs to the Falcons in 2009, Gonzalez has 232 receptions, including 19 for touchdowns, the fourth-most for a tight end in that span.
Information from ESPN.com's Pat Yasinskas and The Associated Press contributed to this report.