In 2012-13 he averaged 15.1 points -- seventh best in the ACC -- and 7.4 rebounds a game for the Wolfpack. The season before he averaged 14.7 points and 7.3 rebounds.
"After discussing this with my family and coach [Mark] Gottfried, I have decided this is the right move for me and my family," Leslie said Monday in a statement.
"Growing up watching N.C. State basketball, I'm honored to have been a part of this program for the past three years. I'm proud to have been a part of helping re-establish the Wolfpack as one of the nation's elite programs."
Leslie started 85 of the 99 games he appeared in for North Carolina State, averaging 13.7 points a game for his career.
He is the second Wolfpack team member to declare for the draft. Lorenzo Brown, a junior guard, said last week he was leaving school to try to join the NBA.