Phinisee attended McCutcheon High School. As a freshman, Phinisee averaged 6.6 points, 1.8 rebounds, and 2.5 assists. In his sophomore year, he averaged 19.0 points, 4.3 rebounds, and 6.2 assists per game helping the Mavericks to a 28-4 overall record and an undefeated 8-0 conference record. The team advanced to the Class 4A state championship game, where they lost 59-62 to New Albany. In his junior year, he averaged 21.7 points, 5.9 rebounds, and 6.8 assists per game. The season ended with a state regional loss 61-68 to Carmel, resulting in a 23-3 overall record. As part of his dominant senior journey, Phinisee was able to tie the all-time scoring record at McCutcheon when he hit a 3-pointer at the buzzer to end the first quarter in the game against Harrison on December 15, 2017. He went on to score a total of 50 points that game to make the record his own. On February 16, 2018 Phinisee and his teammates clinched the North Central Conference title. Phinisee scored 34 points against Muncie Central, despite a broken nose. The season came to an early close with a loss against Zionsville's Eagles, 50-60, leaving the Mavericks with an overall record of 20-5. Phinisee scored 33 points, bringing his total to 2,023. He averaged 29.3 points, 6.8 rebounds, and 5.9 assists per game.
Recruiting
College career
Phinisee was recruited in high school by numerous high profile schools, including scholarship offers from in-state schools Indiana, Purdue, and Butler, and out-of-state schools Georgetown, Virginia, and Xavier. On August 19, 2017, Phinisee announced his commitment to Indiana. Phinisee suffered a concussion at the end of December 2018. He averaged 6.9 points, 3.3 rebounds and 2.9 assists per game as a freshman. He suffered an ankle injury in December 2019.
Career statistics
College
Personal life
Rob is the son of Tanika Phinisee and has three brothers, Alantae, Charles, and Joe. According to his brothers, who also played at McCutcheon High School, his potential began to be recognized when he played alongside Charles in the AAU. His skills and abilities led him to a spot on Indiana Elite's AAU team.
