Irving played for Montclair Kimberley Academy in his freshman and sophomore years in high school. He averaged 26. 5 points, 10. 3 assists, 4. 8 rebounds, and 3. 6 steals and became only the second 1,000 point scorer in the school's history. In his sophomore year, he led MKA to its first New Jersey Prep 'B' state title. After that year, he transferred to St. Patrick High School because he felt he needed a bigger challenge. He had to sit out the first 30 days of St. Patrick's season due to the transfer. At St. Patrick, Irving played with Michael Kidd-Gilchrist, who was widely regarded as one of the best players in the class of 2011. In his first season, Irving averaged 17. 0 points, 5. 0 rebounds, 6. 0 assists and 2. 0 steals per game, and led the team to its third New Jersey Tournament of Champions title in four years. In August 2009, he led the USA East to the tournament title in the Nike Global Challenge. He was the MVP with 21. 3 points and 4. 3 assists per game. The next year, St. Patrick was banned from the state tournament for holding practice prior to the permitted start of the winter sports season. St. Patrick went 24–3 and won the Union County Tournament championship as he finished his senior year with 24. 0 points, 5. 0 rebounds and 7. 0 assists per game.