The Hornblower and Titanic star was amazed that fans from as far as New York, San Francisco and Chicago tapped into cyberspace to give cash to his home charity.
The actor backed Cardiff-based charity Tenovus by taking part in their video "The Rough Guide to Cancer" along with fellow Welsh star Catherine Zeta Jones and Yasmin le Bon.
Fans picked up the details on the internet and donated up to $3,000.
The funds were raised through two Ioan Gruffudd fan clubs - the HMS Hornblower Message Board, run from San Francisco, and the Ioan Gruffudd Mailing List from Chicago.
"I am totally overwhelmed that my internet fans have clubbed together for such a worthy cause," said Ioan.
"It's amazing to think that money has been zipping across the globe through the internet.
"It means a great deal to me personally that my fans should raise money for Tenovus, which is such a true Welsh institution."
'Great cause'
"The Rough Guide to Cancer" teaches young people the risks of cancer including its links with smoking, the benefits of sun cream and the need for a healthy diet.
Free videos were given to all 285 secondary schools in Wales and youth clubs and the project was backed with a £176,000 National Lottery Grant.
Cardiff-born Ioan, who has just finished his next film, Another Life, and has landed a plum role in 102 Dalmations, said: "I agreed to contribute to the video along with Catherine and Yasmin because Tenovus is such a great cause.
"It was a pleasure to be able to do something that may in future help teenagers avoid some of the bad habits that our generation are so fond of, things that increase the risk of cancer."
A spokesman for Tenovus said: "We are overwhelmed with the generosity of Ioan's fans. He obviously has a very bright future if his supporters are so dedicated."