The Barcelona attacker clearly handled the ball before William Gallas netted from close range to break Irish hearts in extra time as the French edged through 2-1 on aggregate.
And Cascarino admits he has lost all respect for Henry and believes he has tarnished his reputation for good by cheating.
“Would you have owned up? In front of 80,000 fans and millions more on television, would you have confessed to handball and wiped out the goal that was sending your nation to the World Cup finals? It’s a matter of conscience,” he said in The Times.
“In that split second when the ball dropped for Henry, it would never have occurred to me to stick out my hand and guide it back into my control. I wasn’t that devious."
Cascarino – who won 88 caps in the famous green and white shirt – admitted in 2000 that he should never have been allowed to play for Ireland.
He only discovered after his international career had ended that he was ineligible and had even been denied an Irish passport in 1985.
He admitted being a ‘fraud’ then, but Cascarino makes no excuses for Henry’s antics in the Stade de France.
“I’m no angel, but I know that I wouldn’t have done what he did," he said.
“And if the roles had been reversed and Ireland had reached South Africa in such a dubious way, would I have been delighted at victory? Of course. Would I have felt it was tainted? Absolutely.
“Henry can say what he likes. No doubt he will plead his innocence. But to me, that handball was pure, calculated cheating.
"He speaks so eloquently, but to me now he’ll always be insincere, a faker, someone who cares only about himself."
Henry lit up the Premier League during his eight-year spell with the Gunners and was part of the French side that won the World Cup on home soil in 1998.
But for all his accolades and admirers over the years, Cascarino believes Henry’s act of deceitfulness has blemished what has otherwise been a glittering career.
“It’s tarnished his reputation for good,” he added.
“Like Diego Maradona, when we reflect in years to come on the career of one of the finest strikers the game has known, we will have to put his handball against Ireland right up there with all the great goals he scored.”
Cascarino has no doubts that football’s governing bodies will merely overlook the incident and lays the blame for cheating in today’s game firmly at their door.
“Cheating in football is commonplace now because the authorities cheat us all by their spineless failure to punish the perpetrators," he said.
“Will Sepp Blatter, the FIFA president, or Michel Platini, the Frenchman who is his UEFA counterpart, condemn Henry, or float the idea that the tie should be replayed?
"Of course not. They will turn a blind eye, and another piece of football’s credibility, another little part of its soul, will quietly die."
