James Phelan, 23, is among the hopefuls auditioning on the ITV talent show this year.
Famous magician Daniels died of cancer in March, aged 77, with his wife Debbie McGee at his side.
Speaking at the show's launch in central London, Holden said: "He was extraordinary (James) and obviously we didn't know anything about Paul at the time."
"I thought of him when Paul passed away, he was the first person I thought of."
She said she thought a magician could win this year.
The popular show returns with Holden, Simon Cowell, David Walliams and Alesha Dixon on the judging panel.
Cowell did not attend the launch as he is currently filming in Los Angeles.
Fellow judge Walliams did not miss a trick and arrived dressed as Cowell on the red carpet.
In a video message, Cowell explained the "official" reason for his absence was due to filming America's Got Talent, but that "unofficially I can't bear to be around David and his ego at the moment".
He joked: "Weeks on the road with him was enough. Just to remind you, I'm on the British show and the American show and David's just on the British show."
:: Britain's Got Talent is broadcast on April 9 at 7pm on ITV.