Tampa Bay Buccaneers won Super Bowl LV in February
NFL teams will play an additional game in the 2021 campaign, the first time in 44 years a change has been made to the regular season.
The extra game will be between teams that finished in the same place from a corresponding division in 2021.
NFL owners also approved the reduction of the number of pre-season games from four to three.
"This is a monumental moment in NFL history," NFL commissioner Roger Goodell said.
Get American Football alerts in the BBC Sport app
The changes had been expected since the NFL and the National Football League Players Association approved the latest collective bargaining agreement in March 2020.
AFC teams will host this year's games before the conferences alternate.
"One of the benefits of each team playing 17 regular-season games is the ability for us to continue to grow our game around the world," Goodell added.
However, the alteration to the structure has not been met with widespread approval.
New Orleans Saints running-back Alvin Kamara last week tweeted that the new format was "dumb as hell".
Green Bay Packers safety Adrian Amos, Philadelphia Eagles cornerback Darius Slay and Saints defensive end Cameron Jordan also expressed their concerns.
The 2021 NFL season is scheduled to begin on Thursday, 9 September and end on Sunday, 9 January. Super Bowl LVI will take place on 13 February at SoFi Stadium in Los Angeles.