"After undergoing a number of tests and evaluations over the past week, Andrew has been diagnosed with leukemia," the family said in a statement released through the university. "He has begun treatments, and we hope everyone will keep him in your thoughts and prayers. This is obviously a difficult situation for our family, and we hope everyone will respect our privacy at this time."
Jones suffered a wrist injury in early December that forced him to miss multiple games, but he's been limited in two games and missed Saturday's game against Baylor with what was considered an unidentified illness.
"Speaking for our entire team and staff, we love Andrew and will do everything we can to support his family and help him get back to health," Longhorns coach Shaka Smart said. "I want to thank everyone for being respectful of the privacy that the Jones family needs at this time."
The 6-foot-4 Jones was a McDonald's All American coming out of MacArthur High School in Irving, Texas. He averaged 11.4 points as a freshman at Texas, but he decided to return for his sophomore season after attending the scouting combine.
Jones returned to the court Dec. 29 and played nine minutes at home in the loss to Kansas. He also played nine minutes in the win at Iowa State on Jan. 1.
Before the wrist injury, Jones was leading the Longhorns in scoring with 15.3 points per game.
His sister, Alexis, was a standout at Baylor and plays for the WNBA champion Minnesota Lynx.
Jones' family has dealt with challenges in the past. Andrew was 7 in 2007 when his father was paralyzed in a car accident on an icy road. Jones was ejected from the car but escaped with only some bruising.
The Associated Press contributed to this report.