Declan Gormley will also receive full costs of his successful action over the contents of two party press releases found to contain defamatory and malicious content.
According to informed sources the legal bill for the three-week trial will run into a six figure sum.
But speaking outside the High Court in Belfast Mr Gormley insisted the case was never about the money.
He said: "What happened to me was wrong, a jury of ordinary men and women have decided it was wrong and have awarded accordingly."
Mr Gormley added that he had no expectations about the level of damages.
"It's never been about the money, it's always been about vindicating my reputation and good name.
"The award is great, but that was never the focus of my action."
The businessman was dismissed along with three other non-executive directors from NI Water in March 2010.
Conor Murphy, the former Sinn Féin Minister for Regional Development, removed them from the board following an independent review team investigation into the awarding of contracts.
A subsequent Stormont Public Accounts Committee report into procurement and performance at the government-owned company was said to have criticised the earlier inquiry and questioned its independence.
Mr Gormley emphatically denies any wrongdoing.
I'm absolutely delighted, but I think it's more important to point out that this completes the utter vindication of my position.
He issued libel proceedings against Sinn Féin and two of its representatives, MLA Cathal Boylan and former Assemblyman Willie Clarke, over the contents of press releases which referred to sacking.
During a three-week hearing, his legal team claimed they damaged his reputation and were reckless if not dishonest.
Lawyers for Sinn Féin contended, however, that neither statement contained any defamatory content. They also claimed a defence of qualified privilege, arguing that the press releases were in response to a campaign of attacks on Mr Murphy mounted by the SDLP with Mr Gormley's collusion.
But on Friday a jury of five men and one woman took just over an hour to unanimously find for Mr Gormley on the balance of probabilities.
They decided both statements were defamatory and contained malicious content.
Mr Justice Gillen then rejected a final defence based on responsible journalism, ruling that no steps had been taken to try to verify the contents of the press releases before publishing them.
In court on Monday the jury was advised against awarding too high a pay-out.
The judge told them: "Keep your feet on the ground."
Counsel for Sinn Féin also argued that the defamation merited only a modest award due to the limited circulation of the press releases.
But Mr Gormley's barrister, David Dunlop, said the party issued the statements to around 200 news outlets in the hope of gaining widespread publicity.
He pointed out how damages were for the distressed suffered by his client, to repair the harm to his reputation and a form of vindication.
Mr Dunlop added that Sinn Féin and the other defendants have not apologised.
Instead there had been "a bull-headed, unreasonable and unjustified persistence in maintaining the party line" throughout the trial," he said.
In a statement Sinn Féin said they would "study this verdict in detail with our legal representatives and examine all options available to us going forward, including the possibility of appeal".