McCarthy, who plays cross dresser Kris Fisher on the Channel 4 soap, arranged a money-can't-buy lot for the White Sapphire Ball, which saw a variety of prizes auctioned off to raise money for Northern Ireland's Children's Hospice.
When the event arrived on Saturday night, the highest bidder in the Hollyoaks auction parted with £4,500 to secure a behind-the-scenes tour of the drama's set at Lime Pictures in Liverpool and film a walk-on part for an episode.
Additionally, the winner will have lunch with the cast and enjoy an evening meal with McCarthy at a Liverpool restaurant before staying the night at a hotel in the city.
McCarthy was joined by his co-stars Emma Rigby (Hannah Ashworth) and Kent Riley (Zak Ramsey) to see the progress of the auction at the weekend.
Speaking afterwards, the 28-year-old actor commented: "I am honoured and privileged to have attended The White Sapphire Ball, to be able to play my part in helping to raise vital funds for the only hospice service for life limited children in Northern Ireland.
"The Hollyoaks auction lot raised a staggering £4,500 - this equates to 450 days of hospice care for one child, and when you think about it in those terms it's very humbling to have been able to do my bit.
"I have to say a huge thank you to our executive producer Tony Wood for making such a fantastic auction lot possible and to Kent Riley and Emma Rigby for coming to Northern Ireland to support this cause and for being great ambassadors for the show."
The event was held at Belfast's Europa Hotel and hosted by Irish TV personalities Gloria Hunniford and John Daly.
