Brissett made the announcement Tuesday night on Twitter. He said he decided to leave school after getting feedback from NBA teams and speaking with family and friends.
He wrote: "I feel the time is right. I am forever grateful for my time at Syracuse and all the love and support I've received from Orange Nation. Through all the ups and downs I've always felt appreciated."
Syracuse coach Jim Boeheim thanked Brissett for his contributions.
Boeheim said in a statement: "He was an important part of two NCAA Tournament teams at Syracuse."
At Syracuse, the native of Mississauga, Ontario, quickly made a name for himself. As a freshman, he averaged 14.9 points and 8.8 rebounds, then fell back as a sophomore, averaging 12.4 points and 7.5 rebounds as he struggled to finish drives to the basket.