	Williams attended North High School. After playing in just one game as a freshman and averaging just 3.5 points as a sophomore, Williams averaged 12.5 points, 10.9 rebounds and 3.3 blocks per game as a junior in 2009–10. As a senior in 2010–11, he averaged 22.1 points, 16.2 rebounds, 4.5 blocks, 2.0 steals, and 1.5 assists, leading North to a Metro Region championship and to the Class 5A quarterfinals. He was named Arizona State Player of the Year that season.