Isaiah was born in Eugene, Oregon. His father, Florian Hartenstein, is a German-American basketball coach and former professional basketball player of African-American heritage.[2] Isaiah's mother is a white American. His parents met in the United States when his father attended and played for the University of Oregon.[3]
In 2008, Hartenstein and his family moved to Germany,[4] where his father was playing professionally.
In the 2013–14 season, Hartenstein led the Artland Dragons' junior team to a German championship in the Under-16 Bundesliga JBBL, while being named Most Valuable Player.[5] He averaged 20.9 points, 12.1 rebounds, 3.4 assists, 2.9 steals and 1.9 blocks on the season.[6] His father Florian, who served as head coach of the team, was named JBBL Coach of the Year.
Hartenstein was selected to play in the 2014 Jordan Brand Classic International Game: He finished the game with four points and five rebounds in 18 minutes.[7]
In August 2015, Hartenstein signed a deal with Lithuanian powerhouse Žalgiris Kaunas, but he remained with the Artland Dragons on loan.[10] The Dragons had withdrawn from the Bundesliga, and were relegated to the 2. Bundesliga ProB, Germany's third division. Hartenstein played in 14 games for the Quakenbrück based side during the 2015–16 campaign, compiling averages of 11.6 points, 8.9 rebounds, 2.1 blocks, 1.6 steals and 1.4 assists.[11]
In January 2016, Hartenstein decided to leave the Artland Dragons to join Žalgiris Kaunas.[12]
Hartenstein made his debut for Žalgiris in Lithuania's top-flight league, the LKL, on September 28, 2016, against Šiauliai[13] and in the EuroLeague against Fenerbahce on October 26.[14] Later in that season, he helped Žalgiris win the first ever King Mindaugas Cup.
Houston Rockets (2018–2020)
In February 2016, Hartenstein attended the "Basketball Without Borders Global Camp" during the NBA All-Star Weekend in Toronto, Canada.[15] On April 7, 2017, he scored 10 points and grabbed three rebounds in 19 minutes of play at the Nike Hoop Summit.[16]
In the 2017–18 campaign, Hartenstein appeared in 38 games of the NBA G League, averaging 9.5 points and 6.6 rebounds a contest for the Rio Grande Valley Vipers.[19]
On July 25, 2018, the Houston Rockets signed Hartenstein.[20] After being sent down to the Rio Grande Valley Vipers, he was suspended one game without pay after leaving the bench during an altercation in a 132–109 loss to the Memphis Hustle on December 17, 2019.[21]
On February 7, 2019, Hartenstein recorded his first career triple-double after posting 12 points, 16 rebounds and 11 assists in a 103–102 road win against Salt Lake City Stars.[22] In the 2018–19 season, Hartenstein scored 33 points and made a career-high 8 3-pointers in the series-clinching game as they won the NBA G League championship with the Rio Grande Valley Vipers.[23] He won the NBA G League Finals MVP award.
On June 23, 2020, the Houston Rockets announced that they had waived Hartenstein.[24]
Denver Nuggets (2020–2021)
On November 30, 2020, the Denver Nuggets announced that they had signed Hartenstein to a multi–year contract.[25] Playing behind the All-Star center Nikola Jokic, Hartenstein averaged 9 minutes, 3.5 points and 2.8 rebounds per game.
Cleveland Cavaliers (2021)
On March 25, 2021, Hartenstein and two future second-round picks were traded to the Cleveland Cavaliers in exchange for center JaVale McGee.[26] In his first twelve games with the Cavs, Hartenstein averaged 19 minutes of playing time and 9 points, 7 rebounds, 2.6 assists and 1.4 blocks per game.[27]
On July 12, 2022, Hartenstein signed a two-year, $16 million contract with the New York Knicks.[29][30]
Oklahoma City Thunder (2024–present)
On July 6, 2024, Hartenstein signed a three-year, $87 million contract with the Oklahoma City Thunder.[31]
On November 20, 2024, Hartenstein made his Thunder debut, putting up 13 points, 14 rebounds, five blocks, and three assists in a 109–99 win over the Portland Trail Blazers.[32]
In August 2017, he made his debut with the German men's national team[37] and took part in EuroBasket 2017, averaging 4.3 points and 2.5 rebounds per game.[38]
