Simmons, 24, made his major-league debut in June 2012 and had his first full season last year but Atlanta decided to offer him a deal that will keep him with the Braves through the 2020 season.
Financial terms weren't released but reports have valued the deal at a total of $58 million.
"We feel that Andrelton is one of the premier shortstops in the game today and we are happy that we were able to agree on this multiyear contract," Braves General Manager Frank Wren said in a release.
Simmons played 157 games last season, hitting. 248 with 17 home runs and 59 runs batted in. He also scored 76 runs. He had a major-league high 499 assists in 2013, earning a Gold Glove.