[6] Then, in 2005, Rozier Jr. spent a few months with his father, who had just been released from prison, before he was arrested again on charges of involuntary manslaughter for his involvement in a robbery and kidnapping from 2003 that had led to the accidental death of an accomplice.

He was named an All-Lake Erie League selection for three years and was 74th in recruiting ranking on ESPNU's Top 100 Players list in 2012.

[11] In his 2012–13 campaign at Hargrave, Rozier averaged 29.3 points, 7.8 rebounds and 5.6 assists while the team went 38–8; he also earned the 2012 Kentucky Derby Festival Basketball Classic MVP and placed second in the dunk and three-point contest that season.

[17] During his rookie season, Rozier received multiple assignments to the Maine Red Claws, Boston's D-League affiliate.

[24] On December 18, he made a steal and go-ahead dunk with 1.5 seconds remaining that gave the Celtics a narrow 112–111 victory over the Indiana Pacers.

[25] On January 31, Rozier logged his first career triple-double in his first NBA start to help the Celtics to a 103–73 victory over the New York Knicks, recording 17 points, 11 rebounds, and 10 assists while becoming just the second player in NBA history with a triple-double in his first start, joining Tony Wroten, who set the initial record on November 13, 2013, with the Philadelphia 76ers.

[27] On March 25, in his sixth start in place of the injured Kyrie Irving, Rozier scored a career-high 33 points in a 104–93 victory over the Sacramento Kings.

[33] On November 9, 2018, Rozier scored a then-season-high 22 points in a 123–115 loss to the Utah Jazz, making his first start of the season in place of Irving.

[39] The contract the Hornets gave to Rozier at that time was criticized following a poor performance in the 2019 playoffs and losing their longtime star Kemba Walker for basically nothing.

However, on May 18, the team's season ended with a 144–117 play-in loss to the Indiana Pacers, which Rozier recorded 16 points, eight rebounds and six assists.

[51] On January 23, 2024, Rozier was traded to the Miami Heat in exchange for Kyle Lowry and a protected first-round draft pick.

[52] The next day, Rozier made his Heat debut, putting up nine points, five assists, four rebounds, and two steals in a 105–96 loss to the Memphis Grizzlies.

[53] Rozier gained social media notoriety due to his appearance on NBA TV's The Starters when he made his 'family recipe' of a sandwich with spaghetti, ranch and sugar.