The Mercury announced Friday that Griner has signed a multiyear deal.
Griner was not shy about wanting to remain with the organization she has played for since being drafted No. 1 overall out of Baylor in 2013.
"Let me just say this and I mean this: If I don't play here, I won't play anywhere, and I mean that," Griner told reporters after the Mercury were eliminated from the playoffs. "I'm not playing for any other organization. I'm Phoenix Mercury until I'm done."
Coming off a 15-19 record in 2019, the Mercury have taken bold steps this week to get back among the Western Conference's elite teams. Re-signing Griner comes after they made separate trades to acquire DeWanna Bonner and Skylar Diggins-Smith.
Last season marked the first time Phoenix hasn't advanced to the Western Conference semifinals since missing the playoffs in 2012 with a 7-27 record.
A six-time All-Star, Griner led the WNBA in scoring with 20.7 points per game and ranked 13th with 7.2 rebounds per game. She has averaged at least 20 points per game in each of the past three seasons.