The NCAA ruled Childs did not submit appropriate paperwork and received impermissible expenses when he worked with an agent while testing his NBA draft prospects. Childs announced in May that he would return to the Cougars for his senior season.
"There was some confusion with this new process, and I made decisions that have caused an outcome that none of us like," Childs said at a news conference Friday. "I just want everyone to know that my intent was never to do something wrong."
BYU athletic director Tom Holmoe said the school is disappointed by the NCAA suspension, which was upheld after BYU appealed.
"Amid the confusion of the NCAA allowing student athletes to sign with agents and still return to school, Yoeli was caught in the transition of a changing landscape," Holmoe said in a statement.
Childs has paid back all the expenses, including interest, the school said.
He averaged 21.2 points and 9.7 rebounds per game last season and was named to the All-West Coast Conference first team for the second straight year.