The deal includes escalator clauses that can take its total to $195 million over five years, Saratsis told ESPN. The contract has not been signed and won't be until Adebayo completes a physical, something that is likely to occur in the next few days.
It will be the richest contract in terms of total value in Heat franchise history, surpassing Jimmy Butler's $141 million deal from last offseason, according to ESPN Stats & Information research.
"This is an accomplishment I always wanted to get," Adebayo said. "Just being able to reach this milestone and being able to generationally change my family's life and also take care of the people around me, it's a big deal to me."
Adebayo will make $5.1 million this season, the final year of his rookie contract. From there, the extension will kick in with a starting salary of somewhere around $28.1 million for the 2021-22 season. And if he makes an All-NBA team or wins another top leaguewide honor this season, his annual salary would only increase.
"It's another challenge I'm willing to take on," Adebayo said. "I'm all about helping this team win. If my individual accolades help, then I'm for sure in."
The Heat had until Dec. 21 to agree with Adebayo on an extension or else would have had to table the matter until next summer. Miami has said the team's intention was to give Adebayo a new deal -- the only question was when. By waiting until next summer, the Heat would have had more salary-cap flexibility.
Adebayo is coming off what was by far the best season of his career. He was an All-Star for the first time, won the skills competition at All-Star Weekend, had the game-saving block of a Jayson Tatum dunk attempt in the final seconds of Miami's Game 1 win over Boston in the Eastern Conference finals and made the NBA All-Defensive Team.
Adebayo averaged 15.2 points, 10.2 rebounds and 5.1 assists this past season. Only one other player in the league had those numbers: two-time reigning MVP Giannis Antetokounmpo of the Milwaukee Bucks. And until Adebayo, no player in Heat history had ever finished a season with those averages in all three categories.
"They going to push you no matter what, whether you've got 160 M's or you've got 1.5. We all get treated the same and that's what I love about this organization," Adebayo said.
Adebayo had told The Associated Press during the NBA's restart earlier this summer at Walt Disney World in Florida that his lone financial goal was to take care of his mother, Marilyn Blount. She raised him by herself in North Carolina, making about $15,000 a year from her multiple jobs and with the family calling a single-wide trailer their home.
"That competitive nature comes out when I feel like I'm playing bad and when things aren't going right," Adebayo said in the September interview with the AP. "I think about how she fought through struggle. ... You see that for 18 years straight, you take that load on and feel that responsibility. And my responsibility is to provide for my mom, and the best way to make sure I can do that is to help us win."
His first plan: to buy his mom a house, wherever she wants.
"To know that she's set for life is a real stress reliever for me," Adebayo said.
The Associated Press contributed to this report.