Jaylen Brown may not even be considered the best player on his own team, but he is now the highest-paid player in NBA history.

Brown agreed to terms on a five-year supermax contract worth up to $304million with the Boston Celtics on Tuesday.

The deal, which is fully guaranteed and includes a trade kicker that would further increase Brown's salary if he's traded, surpasses the $264million contract signed by two-time league MVP and NBA champion Nikola Jokic of the Denver Nuggets last summer.

Brown is a two-time All-Star and was named to the All-NBA second team this past season - his first such honour.

He averaged career highs of 26.6 points, 6.9 rebounds and 3.5 assists - ranking second on the Celtics in all of those categories to Jayson Tatum, who was named to his second consecutive All-NBA first team following this past season.

The Celtics have reached the conference finals in five of Brown's seven pro seasons - including a trip to the 2022 NBA Finals in which they lost to the Golden State Warriors in six games.

Brown averaged 24.6 points on 54.1 per cent shooting and 47.1 per cent from 3-point range in Boston's first two playoff series this past season, but struggled with his shot in the Eastern Conference finals against the Miami Heat and the Celtics were eliminated in seven games.

Against the Heat, he averaged 19 points on 41.8 per cent shooting and connected on just 16.3 per cent of 43 3-point attempts. He misfired on 8 of 9 3-pointers in Game 7.

The third overall pick by Boston in the 2016 NBA Draft, Brown has career averages of 17.9 points, 5.2 rebounds and 2.2 assists.