Leslie J. Lewis, 54, had been charged with kidnapping and assault after his arrest last September at his apartment.
The victim told police that Lewis whipped him with his belt about 40 times, according to court documents. Lewis allegedly took naked pictures of the boy after the whipping.
KOIN reports he pleaded guilty to criminal mistreatment and coercion.
Lewis coached in the "Above the Rim Basketball League," which is not associated with the city or school district.
The boy had been coached by Lewis. He said he was whipped with a belt about 40 times. Someone who heard him yelling for help called police.