Center Isaiah Hartenstein intends to sign a three-year, $75 million contract extension with the Oklahoma City Thunder, a league source confirmed to The Athletic.
Approaching his third season with the organization, Hartenstein has become a fixture in Oklahoma City’s rotation. Over the past two seasons, he started 97 of his 104 regular-season appearances, as well as all 23 games in the Thunder’s run to a 2025 NBA championship. He averaged 9.2 points and 9.4 rebounds this past season, furthering his role beside fellow big man Chet Holmgren.
The No. 4 free agent in John Hollinger’s rankings, Hartenstein originally had a $28.5 million team option for next season, the third of a three-year free-agent contract he signed in 2024. Oklahoma City will instead sign him at a similar annual rate for next season and add two more years to his deal, tying him to the franchise through the 2028-29 season.
The Thunder have been active this offseason to create more financial flexibility to fit Hartenstein into their cap sheet. In the past week, they traded guards Aaron Wiggins and Isaiah Joe to the Atlanta Hawks and Detroit Pistons, respectively, shedding their contracts to try to duck under the NBA’s punitive second-apron threshold.
Hartenstein has played a large role in the Thunder’s league-best defense the past couple of seasons. At 7-foot and 250 pounds, his sturdiness and below-the-rim physicality proved especially useful when defending Spurs center Victor Wembanyama in the Western Conference finals.
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Hartenstein’s passing and screening have helped transform the Thunder offense and introduced new wrinkles built around his playmaking from the high post. He has also given back-to-back MVP Shai Gilgeous-Alexander a bruising screener.
A 2017 second-round pick, the 28-year-old opened his career bouncing between four teams in four seasons — the Houston Rockets, Denver Nuggets, Cleveland Cavaliers and the LA Clippers — while starting just six games in that span. He signed with the New York Knicks in 2022 and became integral in their rise over the next two seasons. With his combination of rebounding, rim protection, physicality and playmaking, Hartenstein became a coveted target during the summer of 2024. He, along with Alex Caruso, became one of the Thunder’s two marquee veteran acquisitions before their title run.