American Idol broadcaster Fox has found no evidence that judge Paula Abdul privately coached one of the talent show's contestants.
Ex-pop star Abdul denied the claims made by Mr Clark
Corey Clark, 25, alleged that Abdul trained him while the pair were conducting a secret affair.
A Fox investigation concluded that Abdul had not given him any special help with his songs or performance.
Abdul, who denied having a relationship with Mr Clark, said she was "grateful this ordeal is over".
Based on the UK's Pop Idol format, American Idol is one of the most popular shows in the US, launching the career of singer Kelly Clarkson and reviving the career of ex-pop star Abdul.
Mr Clark was ejected from its second series in 2003 for concealing a prior arrest.
In May he told the ABC TV network that Abdul, 43, coached him privately on his singing, gave him money for expensive clothes and began a platonic relationship that soon turned sexual.
In July Fox TV set up an independent council to examine his allegations.
Corey Clark, left, made the allegations on ABC's Primetime Live
It said Abdul acknowledged that she had phone conversations with Mr Clark while he was a contestant, but she denied the talks were related to her giving assistance.
The broadcaster concluded that Abdul and Mr Clark's accounts of the phone calls "differ greatly and no evidence was uncovered to resolve the conflicts in their accounts".
Fox said Abdul was expected to return as a judge for the fifth series of the hit show, to be shown in January 2006.
She recently joined Fox's latest reality show So You Think You Can Dance, travelling the US to give dancing tips to the general public.