The 15-year-old was recently cast by bosses at the Channel 4 soap and will begin filming at the show's base in Liverpool later this month.
Coronation Street star Keith announced the news during an appearance on RTÉ's The Late Late Show last night, explaining: "Nobody knows yet, but Jay has been auditioning in the UK for the past few weeks and he found out yesterday that he's going to be one of the new stars in Hollyoaks!"
Keith added that Jay secured the role after an acting agent watched him lead the cast of Peter Pan in a school play.
"I have to say, this is nothing to do with me being in the business at all - an agent came to see him when he was doing Peter Pan," he said. "They were looking for an Irish guy in Hollyoaks. They rang Jay up, he went to London, did an audition, did a screen test, they called him back and they gave him the job."
Writing on Twitter after the chatshow appearance, he added: "Jay Duffy starts in Hollyoaks in a couple of weeks! Very proud of him!"
A Hollyoaks spokesperson confirmed Jay's casting to DS this afternoon but said it was too early to reveal the role he will be playing.
However, fans are already speculating that he will appear as a son of Brendan Brady, played by fellow Dubliner Emmett Scanlan. Viewers have already been introduced to Brendan's estranged wife Eileen but haven't yet seen his children.
Jay's role is a guest part but he will appear on screen for a substantial number of episodes later this year.
Meanwhile, Keith is currently on a break from Coronation Street but will return to filming at the Weatherfield soap in September.
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