Brown’s agent, Jason Glushon, confirmed the agreement yesterday.

The Athletic said the supermax contract extension is fully guaranteed with a trade kicker and no player option.

Brown, 26, has one year remaining on his current contract before the extension kicks in for the 2024-25 season. He will earn US$28.5 million in the upcoming season.

His deal will surpass the current contract of Nikola Jokic, a two-time league Most Valuable Player who signed a five-year, US$276 million contract with the Denver Nuggets.

The Celtics selected Brown with the No 3 overall pick in the 2016 NBA Draft. Last season, he set career highs in points (26.6) and rebounds (6.9) per game to go with 3.5 assists over 67 games. He shot 49.1% from the floor.

In seven seasons, Brown has appeared in 470 games (363 starts), with averages of 17.9 points, 5.2 rebounds and 2.2 assists per game.

The Celtics have made the playoffs in each of Brown’s seasons, losing four times in the Eastern Conference Finals and once in the NBA Finals.