High School
After years of competing against his brother, Taylor, Griffin enrolled at Oklahoma Christian School in 2003, after Taylor. They played under their father, who was the head coach. They played together during the 2003–04 and 2004–05 high school seasons, winning two state high school basketball championships together.In his freshmen year, the Oklahoma Christian Saints posted a perfect 29–0 season and won the Class 3A boys state championship game held at the State Fair Arena against Riverside Indian School, 55–50.[13] In his sophomore year, the Saints repeated as Class 3A state champions, defeating Sequoyah-Tahlequah 51–34, where he scored 12 points to go along with 9 rebounds. The team finished the season with a 24–2 record, with Griffin averaging 13.6 points per game. He was later named to the Little All-City All-State team in what was his final high school season with his brother. After his sophomore year, his brother accepted a scholarship to play college basketball for the University of Oklahoma Sooners. During the summer of 2005, he was a member of the Athletes First AAU team, where he played againstKevin Durant and Ty Lawson's AAU team, the DC Blue Devils.During his junior season, the Oklahoma Christian basketball team was moved down to Class 2A from the Class 3A. As he began his third season with the Saints, he was quickly developing into a strong and athletic player, as he led the Saints to a third straight state championship, scoring 22 points, 9 rebounds and 6 blocks, defeating Washington High School 57–40. He was named the state tournament MVP, and the Saints finished the season 27–1, with Griffin averaging 21.7 points, 12.5 rebounds, and 4.9 assists. For his efforts, he was named The OklahomanPlayer of the Year and to the Tulsa World Boys All-State First Team. His play attracted the attention of the new basketball head coach for Oklahoma, Jeff Capel, who first heard of him through his brother Taylor. That spring, Capel saw him play for the first time and was impressed with his combination of size, strength and athleticism. Capel liked the fact that Griffin had not yet become a household name among recruiters and recruited him because he felt he was the player he needed to rebuild his tenure with the Oklahoma men's basketball program.He had been considering Duke, Kansas, North Carolina and Texas, but his brother eventually sold him on joining Oklahoma when he raved about the direction of the Sooners and the chance to play together again for his home state.
Griffin committed to Oklahoma before the start of his senior season and averaged 26.8 points, 15.1 rebounds, 4.9 assists and 2.9 blocks per game as a senior while leading the team to a 26–3 record. In a game against Oklahoma City Southeast, he finished with an eye-popping triple-double, 41 points, 28 rebounds, and 10 assists. The Saints advanced through the playoffs, defeating Crescent in the quarterfinals and Foyil in the semifinals to earned a berth in the Class 2A state championship. On March 10, 2007, he played his final high school game in the state title game against Pawnee High School. He registered 22 points, 9 rebounds, 6 assists and 2 blocks, as the Saints defeated Pawnee 81–50, winning their fourth straight state title. He was named the Class 2A state tournament MVP for the second consecutive year after averaging 26.6 points per game in the tournament, winning its three games by an average of 30.3 points.During his four-year run, the Oklahoma Christian Saints posted a 106–6 overall record.
Griffin committed to Oklahoma before the start of his senior season and averaged 26.8 points, 15.1 rebounds, 4.9 assists and 2.9 blocks per game as a senior while leading the team to a 26–3 record. In a game against Oklahoma City Southeast, he finished with an eye-popping triple-double, 41 points, 28 rebounds, and 10 assists. The Saints advanced through the playoffs, defeating Crescent in the quarterfinals and Foyil in the semifinals to earned a berth in the Class 2A state championship. On March 10, 2007, he played his final high school game in the state title game against Pawnee High School. He registered 22 points, 9 rebounds, 6 assists and 2 blocks, as the Saints defeated Pawnee 81–50, winning their fourth straight state title. He was named the Class 2A state tournament MVP for the second consecutive year after averaging 26.6 points per game in the tournament, winning its three games by an average of 30.3 points.During his four-year run, the Oklahoma Christian Saints posted a 106–6 overall record.