In 2003, Griffin followed his brother to Oklahoma Christian School, where they played under their father, head coach Tommy Griffin. They played together during the 2003–04 and 2004–05 high school seasons, winning two state basketball championships. In his freshman year, the Oklahoma Christian Saints posted a perfect 29–0 season and won the Class 3A boys state championship game at the State Fair Arena against Riverside Indian School, 55–50. In Griffin's sophomore year, the Saints repeated as Class 3A state champions, defeating Sequoyah-Tahlequah 51–34, where he scored 12 points and grabbed 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. Taylor went on to accept a scholarship to play college basketball for the Oklahoma Sooners. During the summer of 2005, Blake was a member of the Athletes First AAU team, where he played against Kevin Durant and Ty Lawson's AAU team, the DC Blue Devils.