Flynn tweeted the announcement Tuesday, but did not say where he is going. Flynn wrote that the decision was in his best interests at this time.
Flynn, who will be a junior, has been a starter for both his seasons at Washington State. He was the second-leading scorer on the team with an average of 15.8 points per game this season.
On Monday, leading scorer Robert Franks announced that he intends to declare for the NBA draft. Franks averaged 17.4 points per game last season.
The loss of Franks and Flynn is a major blow to coach Ernie Kent's efforts to build a winning program in Pullman.