Rivers, 28, was acquired at the trade deadline from the New York Knicks in a three-team deal that moved George Hill to the Philadelphia 76ers. With the Thunder focused on player development and playing younger players, Rivers wasn't in the team's future plans. Rivers is averaging 7.3 points and 2.0 assists this season in 21 appearances.
After waiving Rivers, though, the Thunder are light in the backcourt, with the team announcing Sunday that starting guard Luguentz Dort has entered the concussion protocol. Dort took a shot to the head on Saturday against the Boston Celtics and exited the game in the third quarter with concussion-like symptoms.
Per the league's protocol, Dort doesn't have a set timetable but will need to clear benchmarks before being available to return to play. Dort, 21, is averaging 12.6 points and is regarded as one of the best backcourt defenders in the league.
The Thunder on Sunday also announced the signing of two-way player Moses Brown to a multiyear deal.
Brown, a 7-foot-1 center who is in his second year, has emerged this month. In Saturday's game against Boston, he had a career-high 21 points and tied a Thunder record with 23 rebounds. In his past nine games, he's averaging 12.4 points and 12.3 rebounds while shooting 61% from the field.
Oklahoma City announced Saturday that veteran center Al Horford would be inactive for the rest of the season, opening the door for Brown to take over the position.
The Thunder originally signed Brown to a two-way contract in Dec. 2020, after he spent the previous season as a two-way player for the Portland Trail Blazers. This season, Brown was named to the All-NBA G League First Team and the NBA G League All-Defensive Team after he averaged 18.9 points, 13.9 rebounds and 1.7 blocks.
The Associated Press contributed to this report.