He was abused by Millwood under the guise of medical examinations in the 1980s when he was aged between 10 and 15.
Millwood was convicted and jailed for four years over the assaults in 2016, and was released on parole in 2019 after serving just over half the sentence.
Civil action was launched by the man against Millwood, 75, three years ago after changes in the law around the statute of limitations.
Supreme Court of Tasmania Chief Justice Alan Blow on Wednesday awarded the man a record breaking $5,313,500 in damages.
He said the man suffered complex post-traumatic stress disorder and a major depressive disorder as a result of the abuse.
He found the man's earning capacity in his corporate career had been impaired since 1999 when he confronted Millwood about the abuse.
Justice Blow said Millwood's contact with his victim escalated over the following four years.
The man would come out of his office to find Millwood standing on the street, and sometimes Millwood would call him. The man changed his phone number at least once, but Millwood tracked it down.
Millwood would make unpleasant comments about the man in the comment sections of newspapers and on social media, claiming the man was delusional and mentally ill.
The man said Millwood had doubled down from prison, writing letters claiming he was the victim of a set up and conspiracy.
"As a result I was the subject of the most malevolent gossip ... these lies became so deeply entrenched that warped versions of them began appearing in social media from people who do not even known me," he said.
The damages include more than $1.5 million for loss of past earning capacity and $2 million for future earning capacity. He will also receive nearly $150,000 for medical expenses and $360,000 for non-economic harm.
The man said the judgment was a "victory for all child abuse survivors".
"This judgment recognises the lifelong impact of child sexual abuse," he said in a statement.
"It recognises that this impact is felt in every facet of life, directly causes physical and psychological injury, and has negative long-term economic consequences."
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