But the cash will only be paid out if the identity of the person behind the slurs is revealed.
The judge at High Court on Wednesday made the award against the unidentified defendant who used two separate pseudonyms during an online hate campaign that lasted for months.
Mr Justice McCloskey said there must be consequences for abuse of social media.
"The courts in Northern Ireland have demonstrated their availability and willingness to protect the interests of those whose legal rights are infringed by the cowardly and faceless perpetrators of this evil," he said.
Writs were issued by the company, two directors and a member of staff last year after a series of messages and information about them was posted on Facebook.
The firm was granted anonymity on the basis that any disclosure would only draw more unwanted public attention.
Barrister Peter Girvan, appearing for the company, said the defendant had written malicious lies about his client, a well-known company.
Although their case against Facebook Ireland Ltd was dismissed, proceedings continued against the second defendant - the person behind the online attacks.
That defendant did not appear in court, and Mr Justice McCloskey held that defamation had been committed.
As this case demonstrated, the laws through the courts penetrates the shields of anonymity and concealment.
The judge said the troll was "hiding behind a mask".
"However, as this case demonstrates on procedural issues our legal system in the modern era adopts a robust and realistic approach," he added.
"As a result the defendant's attempts at concealment and harassment have been thwarted."
He found that libellous postings on Facebook specifically identified at least two of the plaintiffs, while other comments would lead others to identify them through reference and implication.
"The defendant's statements, which are both words and images, took the form of a series of gratuitous and malicious slurs against the character and reputation of the plaintiffs," said Mr Justice McCloskey.
The judge said although the comments were believed to have been widely read, debated and discussed, he decided they were not as widely read as if they had been published in a major newspaper.
However, taking into account the length of time the defamatory comments appeared online, he awarded £20,000 to the plaintiff who suffered the most stress and anxiety. The other two were awarded £10,000 and £5,000.
"In my view this is properly described as a campaign of vilification and abuse which ebbed and flowed during a period of some few months," he said.
If the person behind the attacks is ever identified, they will also be forced to pay legal costs, in a case which the judge described as a "disturbing" growing trend in this type of litigation.
"It's indisputable that social networking sites can be a force for good in society, a truly positive and valuable mechanism," he pointed out.
"However, they are becoming increasingly misused as a medium by which to threaten, abuse, harass, intimidate and defame members of society.
"The solution for this grave mischief is far from clear and lies well beyond the powers of this court. Self-regulation or statutory regulation may well be necessary."