The Australian Electoral Commission took the Queenslander to the Federal Court accusing him of contravening commonwealth requirements by publishing material under a "Redland Hospital: Let's fight for fair funding" Facebook page without adequately disclosing his political links.
The former member for Bowman was fined $20,000 and says he will immediately appeal.
In a judgment published on Wednesday, Justice Darryl Rangiah found Dr Laming contravened the law by posting electoral materials on three dates without ensuring his name and the town or city in which he lives were notified.
One post stated its author was delighted by Dr Laming's announcement of a hospital service funding boost, then claimed to "fact check" the claim before concluding the amount was slightly less.
"I infer Mr Laming thought that by pretending the post was written by someone else, his self-flattery is more likely to be accepted by viewers as true and his achievement admirable," Justice Rangiah said.
One purpose of the post was to disseminate information about funding for the Redland Hospital in Dr Laming's electorate while another was to promote himself.
This could be seen from Dr Laming's deception in pretending the post - which praised himself for obtaining a funding boost - was objective as it was made by someone else.
"I am persuaded by the lengths he went to in perpetrating the deception that his predominant purpose was self-promotion," Justice Rangiah said.
Justice Rangiah found that post to be particularly serious.
"It was not merely a case of Mr Laming omitting to notify his name and relevant town or city, but a deliberate attempt to disguise the fact that he was its author," he said.
"Misleading conduct of that kind strikes at the core of the integrity of our electoral system."
Dr Laming had argued the main purpose of posts was to criticise the Queensland government's funding of Redland Hospital.
Justice Rangiah found two of the five posts complained about by the commission were not in breach of the legislation.
He said the matter had a lengthy and torturous history but by the time the trial started in September Dr Laming had made some admissions.
It was not a case where contraventions occurred in a systemic or organised way and it was unlikely Dr Laming would engage in similar conduct in future.
However, Dr Laming had pretended posts had been published by someone else and the Facebook page concealed that he was its administrator.
The number of viewers of the posts was not large - six for one post and eight for another. The third post was seen by 14 people with nine of those sharing it.
One post that Justice Rangiah found not electoral matter appeared to be an extract of a speech Dr Laming made in parliament, while the other referred to the politician having "ripped Labor a new one over the Hospital".
He fined Dr Laming $10,000 for a post he regarded as especially serious and $5000 each for two others.
Dr Laming told AAP he would immediately appeal the outcome that concerned three posts out of more than 100.
"The posts were factual and completely inadvertent," he said.
Dr Laming was MP for the southeast Queensland seat of Bowman for nearly two decades but did not stand for re-election last year.
