Jaylen Brown has agreed to a record-breaking extension with the Boston Celtics, according to a report.

That’s per The Athletic’s Shams Charania, who notes that Brown’s deal is worth $304 million over 5 seasons. It’s a fully-guaranteed contract and is now the richest deal in NBA history, per the report.

The deal will run through the 2028-29 season and carries an average annual value of more than $60 million.

According to ESPN’s Bobby Marks, the contract will begin at $52.4 million in the 2024-25 season. The deal includes incremental raises and will eventually be worth $69.1 million for the 2028-29 campaign.

Brown’s contract being the richest in NBA history is mostly a product of timing. The NBA’s salary cap — and thus its maximum salary — raised 10% this offseason. Brown is the first player to agree to a super-max contract this offseason.

Brown still has 1 year remaining on his original rookie extension. He’s set to make $28.5 million for the 2023-24 season.

The Celtics are coming off of a disappointing playoff exit to the Miami Heat in the 2023 Eastern Conference Finals. Boston is widely considered to be one of the top teams in the NBA as it prepares for the 2023-24 season.

Jayson Tatum, Brown’s co-star in Boston, still has 3 years remaining — including a player option — on his rookie extension.

Brown averaged a career-high 26.6 points per game last season. He was the No. 3 overall pick out of Cal in the 2016 NBA Draft.