Preston released a statement on Twitter detailing his decision: "We have fully cooperated with the NCAA and were prepared to continue but it has been 67 days since this process began, and still no end in sight."
He continued: "Playing at the University of Kansas was a dream of mine, but being a professional has always been my long-term goal, [and] that day is finally here." He went on to thank Kansas coaches, fans and staff.
Preston has not played a regular-season game for Kansas this season, as the school investigates the "financial picture" of a car he was driving in a single-car crash in early November.
"It's been too long," said Nicole Player, Preston's mother. "They didn't have an answer and weren't prepared to give us answers. He just wants to play."
A five-star prospect in the Class of 2017, Preston was expected to make an immediate impact in the frontcourt for the Jayhawks, who have lacked depth without Preston. ESPN 100 power forward Silvio De Sousa recently enrolled at Kansas, after graduating from high school in December.
BC Igokea announced Preston's signing, as did the Adriatic Basketball Association and Kansas coach Bill Self.
"I can confirm that Billy Preston is foregoing his eligibility to play at Kansas and has signed with a professional team in Bosnia," Self said via statement. "Billy's family has been very upfront telling us that his first choice was to stay at Kansas, but with the uncertainty of the situation they needed to look at other potential options. This opportunity in Bosnia came with a deadline for a decision, and the family reached that decision Friday afternoon.
"We are all disappointed that Billy never had the opportunity to experience college basketball competition but we certainly support him and wish him the best. Although he has been frustrated with the situation, Billy's attitude has been tremendous and he has developed as a person and as a player. I'm sure that will continue as he prepares for his professional career."
Preston did not sign with an agent.
"We are thrilled to welcome Billy Preston to our Club," BC Igokea general manager Igor Dodik said in a release. "We watched him when he was in High School at Oak Hill Academy and in the McDonald's All Star game. We are honored to have such a tremendous talent in our organization. We were watching his situation closely and reached out to his family to show interest and ultimately reached an agreement with the family attorney in California on a contract for the rest of the season. We know Billy is an NBA prospect so we will do our best to continue his development to help him excel for our club and fulfill his goal which is to be an NBA star in the near future.
"BC Igokea will find his place in NBA draft 2018!"
Dodik told ESPN's Jonathan Givony that Preston has signed until the end of the season but that they have a private agreement in the contract that if Preston gets drafted in June, he will pay them a certain amount of money for their efforts in getting him picked.
"It's all defined by the contract," Dodik said "... First of all, we want to give young players opportunity to rise and step forward. ... Our goal is to make our club recognizable in Europe and USA. We want to show ourselves this summer at the NBA draft. Bringing Preston is also good marketing for the club. Those are the main reasons we got him, not money."
Preston is set to make his debut for BC Igokea on Jan. 29, Dodik said. He is set to play in both the Adriatic League and against lower-level competition in the Bosnian league.
Igor Dodik is the son of Milorad Dodik, the president of Republika Srpska, an autonomous region of Bosnia and Herzegovina, and, according to numerous reports, the main sponsor of Igokea. In January, the U.S. Treasury department issued sanctions against Milorad Dodik for "actively obstructing the Dayton Accords," which were the framework of a peace agreement in Bosnia and Herzegovina. According to the treasury department, "Any property or interest in property of Dodik within U.S. jurisdiction is blocked, and U.S. persons are generally prohibited from engaging in transactions with him."
Jeffrey Valle, Billy Preston's lawyer, said he wasn't aware of any allegations against the club and that he would reserve comment until he could conduct more research.