"I'm excited about the opportunity to play under a great coach and for a great program," Stepheson said. "I feel we can be a great team and continue the Carolina winning tradition.
"In my heart I felt North Carolina was the best fit for me. I like the academic support, the chance to grow into a better player and I always dreamed of wearing that Carolina blue uniform playing in the Dean Smith Center."
The 6-9, 220-pound post player chose the Tar Heels over UConn and UCLA. Georgia Tech, Washington, Arizona and Wake Forest were also considered earlier in the process.
"It's awesome to be able to watch a great program like North Carolina have one of the Wolverines play for them now," said Harvard-Westlake Head Coach Greg Hilliard. "It's going to make watching college basketball on the weekends a real treat for me now."
Stepheson averaged 17.0 points, 14.4 rebounds a 3.9 blocks -- including four games in which he had 20 or more rebounds -- his junior season for Harvard-Westlake.
He is ranked the No. 13 center in the class and No. 58 overall by Scout.com
Stepheson is North Carolina's fifth commitment in the senior class, joining Deon Thompson, Tywon Lawson, Wayne Ellington and William Graves. UNC's recruiting class is currently ranked No. 2 in the nation by Scout.com.
For much more on Stepheson, including exclusive video highlights, an expert scouting report and much more, check out the Alex Stepheson Profile