The I'm A Celebrity... contestant gave the cheque after hearing that Dean was being forced to sell memorabilia from the famous ship to pay for her nursing home fees.
According to the Southern Daily Echo, Gest is planning to get his celebrity friends Michael Jackson, Whitney Houston and Steven Seagal to also give cash to the 96-year-old.
He visited Dean's home in Hampshire with ex-Busted singer Matt Willis yesterday.
"I want to be like that when I'm 96," said Gest. "Living in the UK, I thought as an honorary Englishman I could do something good.
"She's a sweetheart, so why should she at 96 have to worry about £3,000 and paying her rent?
"If that money can help her get to sleep at night then I'm just going to have to earn a bit more money to make it up."
Millvina was two months old when the Titanic sank, killing 1,500 people on its maiden voyage.