Per ESPN's Adrian Wojnarowski, the deal is for two years and $25.2 million.
Adams was already under contract for next season, but now he'll be tied to Memphis for three years and $43.1 million.
The contract rewards a steady presence for the Grizzlies, both on and off the court, as they posted the NBA's second-best record last season. The 29-year-old big man, who landed on the team via a trade from the New Orleans Pelicans, averaged 6.9 points, 10.0 rebounds and 3.4 assists in 26.3 minutes per game while shooting 54.7% from the field.
In an offense with plenty of shooters and slashers — such as Ja Morant, Jaren Jackson Jr. and Desmond Bane — Adams' willingness to the dirty work made him a perfect fit. He was first in the NBA in screen assists, first in offensive rebounding rate and second in loose balls recovered on offense, plus he led the Grizzlies in assists among non-point guards.
Every great offense could use a Steven Adams, so Memphis naturally wanted to keep him around. The Grizzlies have, for the most part, opted to keep last year's 56-win team together this offseason, with their most notable departures being Kyle Anderson, who signed with the Minnesota Timberwolves, and De'Anthony Melton, traded to the Philadelphia 76ers for Danny Green.
The biggest move was another contract extension, a $231 million max extension for Morant.
The real work will begin when the season begins, as the team is very clearly interested in becoming a real rival to the defending champion Golden State Warriors.