Brown can secure up to $8 million in incentives if he wins MVP or Defensive Player of the Year, or makes an All-NBA team, league sources told Yahoo Sports' Chris Haynes.
The guard will make $4 million in bonuses if the Celtics win at least 49 games or reach the second round of the playoffs, or if he plays in 65 or more games, adds Haynes.
Brown is entering the final season of the four-year, $21-million contract he signed after he was drafted third overall in 2016. He would have become a restricted free agent next summer if a new deal was not reached and Boston tendered him a qualifying offer.
"Jaylen has made tremendous strides over the last three years and has become a fantastic player for us on both ends of the court," Celtics president of basketball operations Danny Ainge said in a statement.
The 22-year-old averaged 13 points on 46.5% shooting across 74 appearances last season. His scoring and 3-point shooting numbers dipped from the previous campaign and he lost his starting position after playing a major role in the club's run to the Eastern Conference finals in 2018.
"He's a great person and hard worker, who at 22 years old, can score and defend against the best players in the NBA," Ainge added. "Jaylen is a true professional who did a great job accepting his role last season, and he is a major part of our championship goals."
Brown is set to make $6.5 million this season.