While a BBC inquiry found minor errors in her account of Ian Parker's treatment at the British Home and Hospital for Incurables, her "journalistic integrity was not in doubt".
And the inquiry reprimanded John Ware, a freelance journalist who has produced respected work for Panorama and Rough Justice, for making his criticism of the programme in a Sunday Telegraph article last August.
Mr Ware, who himself has a friend at the hospital for brain-injured patients, said the programme on advocacy had "twisted the facts" and used a hidden camera in the hospital without justification.
The BBC's own complaints unit said of The Rantzen Report: "The programme makers drew reasonable conclusions from the evidence available to them and their journalistic integrity is not in doubt.
"In the light of later evidence made available to the inquiry, it appears that the programme contained some errors. Though these were minor in themselves, they involved a degree of unfairness to the hospital. This didn't invalidate, however, the programme's overall argument on the topic of advocacy."
A BBC spokesman said yesterday: "John Ware has been told both verbally and in writing that he is contractually bound to clear all articles for the press about broadcasting and the BBC. He has been reprimanded for raising the issue as he did."
Viewers' complaints about The Rantzen Report which followed Mr Ware's article will be dealt with in the BBC's quarterly complaints bulletin.
After seeking clarification of the report from senior BBC staff at the BBC, Ms Rantzen said: "I am delighted that they [the BBC] completely refute John Ware's unfounded allegations against me that I `twisted the facts' and `perverted the truth'.
"I am delighted that my journalistic integrity has therefore been completely vindicated."
The programme had thoroughly checked the claims of Mr Parker's mother Janet that he lacked stimulation, she said.
Ms Rantzen has just signed a new two-year contract with BBC TV. The chat show Esther, now broadcast twice a week, will become a five-days- a-week show next year.
She will host Childwatch Plus Ten, a 10th anniversary programme about one of Ms Rantzen's most famous and long-lived campaigns to counter child abuse, on 30 October.