Turner announced the move Monday in a video posted on YouTube. The 6-foot-11 forward has long been projected as a potential lottery pick in the draft. The announcement came two days after Texas coach Rick Barnes was fired after 17 seasons.
Turner was one of the nation's most prized recruits out of high school. He averaged 10.1 points, 6.5 rebounds and 2.6 blocks as the Longhorns went 24-10 and lost in the first round of the NCAA Tournament.
But he started only seven games and averaged 22 minutes as Barnes often left him on the bench for long stretches.
Texas did not immediately comment.