The Boston Celtics have officially moved on from starting point guard Kemba Walker and will be bringing back a familiar name in the process.

The Boston Globe reports the Celtics have agreed to send Walker, the No. 16 pick in the 2021 NBA Draft and a 2025 second-round pick to the Oklahoma City Thunder in exchange for former Celtics forward Al Horford, center Moses Brown and a 2023 second-round pick, according to a league source.

The trade is the first transaction made during former head coach Brad Stevens' tenure as the Celtics' president of basketball operations after Stevens was promoted in the absence of a retiring Danny Ainge earlier this month.

Horford is currently signed to a four-year, $53 million deal originally signed with the Philadelphia 76ers two seasons ago, before being traded to Oklahoma City last year. The veteran big man appeared in 28 games before during the 2020-21 season before being deactivated so the team could focus on developing younger players.

Brown, 21, was given a two-way contract and flourished in the NBA G League before being promoted to the Thunder in March, which included a breakout 21-point, 23-rebound performance against the Celtics one day after being promoted.

Bleacher Report's Farbod Esnaashari initially reported both Walker and the Boston Celtics were "likely to move forward from their relationship this offseason in a mutual agreement between the parties" earlier this month.

Esnaashari reports the possible breakup stems from "a rift" between Walker and Ainge prior to stepping down as team president.

Ainge reportedly tried to trade Walker for now-Milwaukee Bucks guard Jrue Holiday during the 2020 offseason.

"The feeling is mutual between Walker and the organization," Esnaashari reported, adding both sides were reportedly looking to move on.

Walker is still owed $36 million from his contract for 2021-22 and a $37.7 million player option in 2022-23 that he's expected to take given injury concerns in 2020-21.

Walker, a four-time NBA All-Star, averaged 19.3 points per age, 4.9 assists and 3.6 rebounds in 43 games for the Celtics during the 2020-21 season.

The former UConn standout was selected at No. 9 overall by the then-Charlotte Bobcats and spent eight seasons in the Queen City before signing with the Celtics in 2019.

AM 570 LA Sports Newsletter