Asked about his late father Peter Walsh, he said: "He's sitting up now in heaven looking down, cap in his hands, he took care of me."
Sitting on the opposite side of the courtroom to her painter and decorator stepson, Mrs Walsh, wearing a black evening dress with a pearl necklace and grey cardigan, went pale and shook her head as the ruling was given.
Outside the Four Courts, she told the Irish Daily Mail she was disappointed with the outcome and vowed to appeal.
An ecstatic Mr Walsh told reporters he just wanted to "get on with my life", adding: "I'm out of here", before making a quick departure.
The mother-of-two won the jackpot six years ago with a ticket that was signed by six family members including herself - yet she believed that she could do as she pleased with the money.
She gave gifts of as little as £86,000 (NZ$147,682) to one signatory - a nephew of her husband. The court heard the biggest gift she gave was £392,000 (NZ$673,158) to one of her sons - even though an equal one-sixth share of the £2.9million (NZ$4.98m) prize money came to £485,738 (NZ$834,128).
Last night, at the highly charged conclusion of a seven-day hearing, Judge Richard Humphreys rejected Mrs Walsh's version of events and awarded Mr Walsh £484,000 (NZ$831,144).
The judge said Mrs Walsh was a woman "capable of very significant calculation and design."
The judge gave the ruling despite pleas from Mrs Walsh's counsel, Michael Delaney, that Mr Walsh cannot "receive an entirely undeserved windfall in excess of £430,000 (NZ$738,413)." The judge said Mrs Walsh gave unreliable testimony from the witness box this week and that she 'ducked and weaved' in her attempts to defend herself.
The ruling raises the prospect that other family members could now come forward to claim their own shares. Last night, legal experts said the judgment "would certainly increase their chances" of them seeking a larger share.
The ruling also sets a guideline for future Lottery winners - indicating that winnings should be distributed equally in cases where more than one person has signed the ticket. Under National Lottery rules, anyone who signs the back of a winning ticket is entitled to benefit.
However, former Lotto claims manager Eamonn Hughes told the court this week that exactly how winnings are distributed "was none of our concern."
In court, Mrs Walsh, of Perssepark, Ballinasloe, Co. Galway, insisted that she had given her stepson the choice of a £171,953 (NZ$295,284) cash gift or her £116,068 (NZ$199,316) house - and that Mr Walsh opted for the house.
During the seven-day hearing, she said: "Because they [Mr Walsh and his father Peter] had been estranged from the year before, and there had been no contact, and he came back three weeks before I won the Lotto, I felt he didn't deserve it."
She said that despite her 'reservations', she had given her "beautiful" home to the 52-year-old, and he "wouldn't have got the house only for the Lotto win."
The court has also heard that stepson David Walsh was seen as "not much of a worker" and that he was once divorced after getting married in the US.
Mrs Walsh told Judge Richard Humphreys: "We were afraid that some of his wives could come along and make a claim against him."
The 65-year-old businesswoman claimed, on day five of the remarkable case, that painter and decorator Mr Walsh "never once asked for any share in the Lotto".
Mr Walsh, of Knocknagreena, Ballinasloe, always insisted that his late father - who died in December 2011 - had intended him to have the house, regardless of the Lotto win.
But Mrs Walsh had counter-sued her stepson, claiming that if he won the case for a share of the jackpot, then she should get her old house back because it would amount to "unjust enrichment" otherwise.
Giving his ruling after deliberating for about 30 minutes, Judge Humphreys said it was "not inherently plausible" that Mr Walsh accepted a house worth £116,068 (NZ$199,316) instead of £171,953 (NZ$295,284) cash.
The judge observed that there was "no reason the plaintiff [Mr Walsh] would do himself out of £55,884 (NZ$959,66)".
The ruling means that Mr Walsh will keep the house and get his £484,000 (NZ$831,144) share of the jackpot.
Earlier, during legal arguments, lawyers for Mrs Walsh said she never intended anyone who signed the ticket or the Lotto declaration form to receive "a portion of the prize as of right".
Instead, she intended "that such persons would receive payment of such amount of money as she in her discretion saw fit to make to them," the court heard.
Dervla Browne SC, for Mr Walsh, told the court that all six people who signed the ticket, including David Walsh, were entitled to benefit equally from the £2.9million (NZ$4.98m).
Later, Judge Humphreys ruled that Mrs Walsh had "made a conscious and deliberate decision to swear an affidavit she knew was false" and had done so in order to "conceal her assets from persons including the plaintiff [Mr Walsh]".
The temporary freezing injunction on Mrs Walsh's assets - designed to protect the award of £484,000 (NZ$831,144) in her stepson's favour - will last until Monday, when the case will come before the court again.
She has 28 days to lodge an appeal. Outside the court, she agreed she was disappointed by the ruling. Asked if she will appeal, she said: "Yes."
