Hamilton spent two seasons with the Tigers after transferring from Iowa State as a sophomore. He started 32 of 33 games for LSU this past season, averaged 12.9 points and 7.2 rebounds per game and was named a second-team All-SEC selection.
"I will graduate next month and I am getting married this summer. I am ready to take the next step in my life," Hamilton said in a prepared statement. "Again, I would like to thank everyone that has helped me along the way and especially the fans here at LSU."
The loss of Hamilton, who averaged about 30 minutes a game, leaves the Tigers with quite a hole in their post game. LSU already was losing senior forward Storm Warren.
Hamilton, a 7-foot, 260-pound center from Alpine, Utah, is not rated in ESPN NBA Insider and draft analyst Chad Ford's Top 100 draft prospects.
"Justin Hamilton has done a good job for the LSU basketball program," Tigers coach Trent Johnson said in the release. "His development from the time he arrived prior to the 2010-11 season has been very impressive.
"During this process, our responsibility as a basketball staff was to make sure we educated Justin and his family of the many challenges that will lie in front of him. He will graduate from LSU this semester and will have his degree in hand. I and the members of our program wish him nothing but the best in his future."