Along with Walker and the No. 16 overall pick in 2021, the Celtics are also sending a 2025 second-round pick to the Thunder in exchange for Horford, Moses Brown and a 2023 second-rounder, sources said.
The trade comes after a disappointing season for Walker, who missed the final two games of the Celtics’ first-round loss to the Brooklyn Nets with a bone bruise in his left knee. After Boston was eliminated, Walker said he needed to focus on getting healthy after dealing with left knee issues for most of 2020 that caused him to miss the start of the 2020-21 season. He missed 29 regular-season games in all.
The four-time All-Star has two years and more than $73 million remaining on his contract.
Horford will rejoin the Celtics, where he played from 2016 to 2019, earning an All-Star nod in 2018. He was shut down for the final 28 games of this season as the Thunder limped to a 22-50 finish.
Information from ESPN’s Tim Bontemps and Royce Young was used in this report.