"He's such a quality guy," White Sox president Ken Williams said of Grandal. "And for him to understand our messaging, our goals, our path, and to say, 'I want to be a part of that and I'm going to commit to it early so we can move on to the next thing heading into the winter meetings,' [it] just shows what kind of character we're talking about."
It is the biggest contract in the history of the White Sox franchise. Grandal, 31, will receive $18.25 million per season through 2023.
"There's a lot of young talent,'' Grandal said. "The way I looked at it, this team could be a dark horse in the next year or so.''
He bet on himself to have a big year. It paid off.
After signing a one-year, $18.25 million contract with the Milwaukee Brewers, the switch-hitting Grandal posted career highs in homers (28) and RBIs (77) and earned his second All-Star appearance. He walked over 100 times to post a .380 OBP, which ranked first among major league catchers.
He also led all catchers in games played (153) and was second in extra-base hits (56), total bases (240) and RBIs.
Grandal declined to exercise his part of a $16 million mutual option with the Brewers for 2020, with a $2.25 million buyout, so he could again become a free agent.
"Unlike last year around this time, where the market was kind of completely nonexistent, this year was just slightly different,'' Grandal said. "It seemed like there were several teams that were working hard within their limits to be able to compete. There were several teams that were really interested. The one thing that kind of stood out the most for me is the White Sox. I love their professionalism, their preparation and the direction of the program.''
General manager Rick Hahn said he met with Grandal at the general managers meetings in Arizona last week and reached an agreement on Wednesday night.
"Exciting day for us around here, being able to add one of the elite talents at a premium position," Hahn said.
The White Sox went 72-89 in their seventh straight losing season and missed the playoffs for the 13th time in 14 years since the 2005 team won the World Series.
James McCann, 29, was the White Sox's starting catcher last season and was an All-Star for the first time, hitting .273 with 18 home runs and 60 RBIs. He is signed for the 2020 season with a contract that carries a base salary of $4.9 million.
Hahn said either could be used at designated hitter, with Grandal also getting time at first base.
"Having too many guys who are quality big leaguers is a good thing," Hahn said. "Not something that we necessarily view as a problem."
With young players establishing themselves in the majors and promising prospects in the minors, the White Sox think they are setting themselves up to make a big jump.
"This was all planned, going back five years ago when we started this and started thinking about [rebuilding]," Williams said. "We get ourselves in position with our young core and we could augment it with guys like this.
"... Clearly, we're trying to put ourselves in a window that could very well start next year but extend to the next five to seven years."
Offensely, Tim Anderson led the majors with a .335 batting average, and Yoan Moncada had a breakthrough season, hitting .315 with 25 homers and 79 RBIs. Eloy Jimenez showed pop as a rookie, with a .267 average, 31 homers and 79 RBIs.
Prized outfielder Luis Robert figures to debut next spring, and promising second baseman Nick Madrigal also is in the pipeline.
"I'm not going to prognosticate how this plays or how people should interpret it or what this means in terms of what we're going to do next,'' Hahn said. "Generally, in my experience, people don't want to hear about the labor; they want to see the baby. We had a boy today, I guess. ... My point being the impact this has on future deals, we'll talk about after there's future deals.''
Grandal, who leads all major league catchers with 117 homers since 2015, has a career .241 batting average with 141 home runs, 416 RBIs and 374 runs scored over eight seasons with the Brewers, Dodgers and San Diego Padres.
White Sox manager Rick Renteria was the bench coach for the Padres while Grandal was with San Diego.
To make room on the roster for Grandal, the White Sox designated outfielder Daniel Palka for assignment.
ESPN's Jeff Passan and The Associated Press contributed to this report.