The challenge involves charities competing to encourage their supporters to use Everyclick, a search engine which donates part of its revenues to a charities of its users' choice and provides other fundraising services.
Polly Gowers, founder of Everyclick, said: "Marie Curie were the clear winners, and had explored every possible avenue to get their supporters fundraising using the Everyclick tools, from donations to search and sponsorship, they had maximised opportunities to fundraise online."
Marie Curie won both the overall prize and the category for charities with a large donor base, while Epilepsy Action won the medium donor category and Endometriosis UK won the small donor category.
Free advertising on Everyclick was awarded the medium and small categories prizes.
Marie Curie will now work with Clear Channel Outdoor and Everyclick to launch a national advertising campaign to raise awareness of the charity's work and provide support for cancer patients and their families.